- NAME
- SYNOPSIS
- DESCRIPTION
- EXAMPLE
- WARNING
- GLOSSARY
  - M
  - _
  - a
  - b
  - c
  - d
  - e
  - f
  - g
  - h
  - i
  - k
  - l
  - m
  - n
  - o
  - p
  - r
  - s
  - t
  - u
  - v
  - z
- NOTE

# NAME

Config - access Perl configuration information

# SYNOPSIS

        use Config;
        if ($Config{'cc'} =~ /gcc/) {
            print "built by gcc\n";
        }

        use Config qw(myconfig config_sh config_vars);

        print myconfig();

        print config_sh();

        config_vars(qw(osname archname));

# DESCRIPTION

The Config module contains all the information that was available to the `Configure` program at Perl build time (over 900 values).

Shell variables from the config.sh file (written by Configure) are stored in the readonly-variable %Config, indexed by their names.

Values stored in config.sh as 'undef' are returned as undefined values. The perl exists function can be used to check if a named variable exists.

myconfig()

  Returns a textual summary of the major perl configuration values. See also -V in Switches.

config_sh()

  Returns the entire perl configuration information in the form of the original config.sh shell variable assignment script.

config_vars(@names)

  Prints to STDOUT the values of the named configuration variable. Each is printed on a separate line in the form:

        name='value';

  Names which are unknown are output as `name='UNKNOWN';`. See also `-V:name` in Switches.

# EXAMPLE

Here's a more sophisticated example of using %Config:

        use Config;
        use strict;

        my %sig_num;
        my @sig_name;
        unless($Config{sig_name} && $Config{sig_num}) {
            die "No sigs?";
        } else {
            my @names = split ' ', $Config{sig_name};
            @sig_num{@names} = split ' ', $Config{sig_num};
            foreach (@names) {
                $sig_name[$sig_num{$_}] ||= $_;
            }
        }

        print "signal #17 = $sig_name[17]\n";
        if ($sig_num{ALRM}) {
            print "SIGALRM is $sig_num{ALRM}\n";
        }

# WARNING

Because this information is not stored within the perl executable itself it is possible (but unlikely) that the information does not relate to the actual perl binary which is being used to access it.

The Config module is installed into the architecture and version specific library directory ($Config{installarchlib}) and it checks the perl version number when loaded.

The values stored in config.sh may be either single-quoted or double-quoted. Double-quoted strings are handy for those cases where you need to include escape sequences in the strings. To avoid runtime variable interpolation, any `$` and `@` characters are replaced by `\$` and `\@`, respectively. This isn't foolproof, of course, so don't embed `\$` or `\@` in double-quoted strings unless you're willing to deal with the consequences. (The slashes will end up escaped and the `$` or `@` will trigger variable interpolation)

# GLOSSARY

Most Config variables are determined by the `Configure` script on platforms supported by it (which is most UNIX platforms). Some platforms have custom-made Config variables, and may thus not have some of the variables described below, or may have extraneous variables specific to that particular port. See the port specific documentation in such cases.

## M

Mcc

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the Mcc program. After Configure runs, the value is reset to a plain Mcc and is not useful.

## _

_a

  From Unix.U:

  This variable defines the extension used for ordinary libraries. For unix, it is .a. The . is included. Other possible values include .lib.

_exe

  From Unix.U:

  This variable defines the extension used for executable files. For unix it is empty. Other possible values include .exe.

_o

  From Unix.U:

  This variable defines the extension used for object files. For unix, it is .o. The . is included. Other possible values include .obj.

## a

afs

  From afs.U:

  This variable is set to true if AFS (Andrew File System) is used on the system, false otherwise. It is possible to override this with a hint value or command line option, but you'd better know what you are doing.

alignbytes

  From alignbytes.U:

  This variable holds the number of bytes required to align a double. Usual values are 2, 4 and 8.

ansi2knr

  From ansi2knr.U:

  This variable is set if the user needs to run ansi2knr. Currently, this is not supported, so we just abort.

aphostname

  From d_gethname.U:

  Thie variable contains the command which can be used to compute the host name. The command is fully qualified by its absolute path, to make it safe when used by a process with super-user privileges.

apiversion

  From patchlevel.U:

  This is a number which identifies the lowest version of perl to have an API (for XS extensions) compatible with the present version. For example, for 5.005_01, the apiversion should be 5.005, since 5.005_01 should be binary compatible with 5.005. This should probably be incremented manually somehow, perhaps from patchlevel.h. For now, we'll guess maintenance subversions will retain binary compatibility.

ar

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the ar program. After Configure runs, the value is reset to a plain ar and is not useful.

archlib

  From archlib.U:

  This variable holds the name of the directory in which the user wants to put architecture-dependent public library files for $package. It is most often a local directory such as /usr/local/lib. Programs using this variable must be prepared to deal with filename expansion.

archlibexp

  From archlib.U:

  This variable is the same as the archlib variable, but is filename expanded at configuration time, for convenient use.

archname

  From archname.U:

  This variable is a short name to characterize the current architecture. It is used mainly to construct the default archlib.

archobjs

  From Unix.U:

  This variable defines any additional objects that must be linked in with the program on this architecture. On unix, it is usually empty. It is typically used to include emulations of unix calls or other facilities. For perl on OS/2, for example, this would include os2/os2.obj.

awk

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the awk program. After Configure runs, the value is reset to a plain awk and is not useful.

## b

baserev

  From baserev.U:

  The base revision level of this package, from the .package file.

bash

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

bin

  From bin.U:

  This variable holds the name of the directory in which the user wants to put publicly executable images for the package in question. It is most often a local directory such as /usr/local/bin. Programs using this variable must be prepared to deal with ~name substitution.

binexp

  From bin.U:

  This is the same as the bin variable, but is filename expanded at configuration time, for use in your makefiles.

bison

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

byacc

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the byacc program. After Configure runs, the value is reset to a plain byacc and is not useful.

byteorder

  From byteorder.U:

  This variable holds the byte order. In the following, larger digits indicate more significance. The variable byteorder is either 4321 on a big-endian machine, or 1234 on a little-endian, or 87654321 on a Cray ... or 3412 with weird order !

## c

c

  From n.U:

  This variable contains the \c string if that is what causes the echo command to suppress newline. Otherwise it is null. Correct usage is

              $echo $n "prompt for a question: $c".

castflags

  From d_castneg.U:

  This variable contains a flag that precise difficulties the compiler has casting odd floating values to unsigned long:

              0 = ok

              1 = couldn't cast < 0

              2 = couldn't cast >= 0x80000000

              4 = couldn't cast in argument expression list

cat

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the cat program. After Configure runs, the value is reset to a plain cat and is not useful.

cc

  From cc.U:

  This variable holds the name of a command to execute a C compiler which can resolve multiple global references that happen to have the same name. Usual values are cc, Mcc, `cc -M`, and `gcc`.

cccdlflags

  From dlsrc.U:

  This variable contains any special flags that might need to be passed with `cc -c` to compile modules to be used to create a shared library that will be used for dynamic loading. For hpux, this should be +z. It is up to the makefile to use it.

ccdlflags

  From dlsrc.U:

  This variable contains any special flags that might need to be passed to cc to link with a shared library for dynamic loading. It is up to the makefile to use it. For sunos 4.1, it should be empty.

ccflags

  From ccflags.U:

  This variable contains any additional C compiler flags desired by the user. It is up to the Makefile to use this.

cf_by

  From cf_who.U:

  Login name of the person who ran the Configure script and answered the questions. This is used to tag both config.sh and config_h.SH.

cf_email

  From cf_email.U:

  Electronic mail address of the person who ran Configure. This can be used by units that require the user's e-mail, like MailList.U.

cf_time

  From cf_who.U:

  Holds the output of the date command when the configuration file was produced. This is used to tag both config.sh and config_h.SH.

chgrp

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

chmod

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

chown

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

clocktype

  From d_times.U:

  This variable holds the type returned by `times().` It can be long, or clock_t on `BSD` sites (in which case <sys/types.h> should be included).

comm

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the comm program. After Configure runs, the value is reset to a plain comm and is not useful.

compress

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

contains

  From contains.U:

  This variable holds the command to do a grep with a proper return status. On most sane systems it is simply grep. On insane systems it is a grep followed by a cat followed by a test. This variable is primarily for the use of other Configure units.

cp

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the cp program. After Configure runs, the value is reset to a plain cp and is not useful.

cpio

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

cpp

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the cpp program. After Configure runs, the value is reset to a plain cpp and is not useful.

cpp_stuff

  From cpp_stuff.U:

  This variable contains an identification of the catenation mechanism used by the C preprocessor.

cppflags

  From ccflags.U:

  This variable holds the flags that will be passed to the C pre- processor. It is up to the Makefile to use it.

cpplast

  From cppstdin.U:

  This variable has the same functionality as cppminus, only it applies to cpprun and not cppstdin.

cppminus

  From cppstdin.U:

  This variable contains the second part of the string which will invoke the C preprocessor on the standard input and produce to standard output. This variable will have the value `-` if cppstdin needs a minus to specify standard input, otherwise the value is ``''.

cpprun

  From cppstdin.U:

  This variable contains the command which will invoke a C preprocessor on standard input and put the output to stdout. It is guaranteed not to be a wrapper and may be a null string if no preprocessor can be made directly available. This preprocessor might be different from the one used by the C compiler. Don't forget to append cpplast after the preprocessor options.

cppstdin

  From cppstdin.U:

  This variable contains the command which will invoke the C preprocessor on standard input and put the output to stdout. It is primarily used by other Configure units that ask about preprocessor symbols.

cryptlib

  From d_crypt.U:

  This variable holds -lcrypt or the path to a libcrypt.a archive if the `crypt()` function is not defined in the standard C library. It is up to the Makefile to use this.

csh

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the csh program. After Configure runs, the value is reset to a plain csh and is not useful.

## d

d_Gconvert

  From d_gconvert.U:

  This variable holds what Gconvert is defined as to convert floating point numbers into strings. It could be `gconvert` or a more `complex` macro emulating gconvert with `gcvt()` or sprintf.

d_access

  From d_access.U:

  This variable conditionally defines `HAS_ACCESS` if the `access()` system call is available to check for access permissions using real IDs.

d_alarm

  From d_alarm.U:

  This variable conditionally defines the `HAS_ALARM` symbol, which indicates to the C program that the `alarm()` routine is available.

d_archlib

  From archlib.U:

  This variable conditionally defines `ARCHLIB` to hold the pathname of architecture-dependent library files for $package. If $archlib is the same as $privlib, then this is set to undef.

d_attribut

  From d_attribut.U:

  This variable conditionally defines `HASATTRIBUTE`, which indicates the C compiler can check for function attributes, such as printf formats.

d_bcmp

  From d_bcmp.U:

  This variable conditionally defines the `HAS_BCMP` symbol if the `bcmp()` routine is available to compare strings.

d_bcopy

  From d_bcopy.U:

  This variable conditionally defines the `HAS_BCOPY` symbol if the `bcopy()` routine is available to copy strings.

d_bsd

  From Guess.U:

  This symbol conditionally defines the symbol `BSD` when running on a `BSD` system.

d_bsdgetpgrp

  From d_getpgrp.U:

  This variable conditionally defines `USE_BSD_GETPGRP` if getpgrp needs one arguments whereas `USG` one needs none.

d_bsdsetpgrp

  From d_setpgrp.U:

  This variable conditionally defines `USE_BSD_SETPGRP` if setpgrp needs two arguments whereas `USG` one needs none. See also d_setpgid for a POSIX interface.

d_bzero

  From d_bzero.U:

  This variable conditionally defines the `HAS_BZERO` symbol if the `bzero()` routine is available to set memory to 0.

d_casti32

  From d_casti32.U:

  This variable conditionally defines CASTI32, which indicates whether the C compiler can cast large floats to 32-bit ints.

d_castneg

  From d_castneg.U:

  This variable conditionally defines `CASTNEG`, which indicates wether the C compiler can cast negative float to unsigned.

d_charvspr

  From d_vprintf.U:

  This variable conditionally defines `CHARVSPRINTF` if this system has vsprintf returning type (char*). The trend seems to be to declare it as ``int `vsprintf()''.`

d_chown

  From d_chown.U:

  This variable conditionally defines the `HAS_CHOWN` symbol, which indicates to the C program that the `chown()` routine is available.

d_chroot

  From d_chroot.U:

  This variable conditionally defines the `HAS_CHROOT` symbol, which indicates to the C program that the `chroot()` routine is available.

d_chsize

  From d_chsize.U:

  This variable conditionally defines the `CHSIZE` symbol, which indicates to the C program that the `chsize()` routine is available to truncate files. You might need a -lx to get this routine.

d_closedir

  From d_closedir.U:

  This variable conditionally defines `HAS_CLOSEDIR` if `closedir()` is available.

d_const

  From d_const.U:

  This variable conditionally defines the `HASCONST` symbol, which indicates to the C program that this C compiler knows about the const type.

d_crypt

  From d_crypt.U:

  This variable conditionally defines the `CRYPT` symbol, which indicates to the C program that the `crypt()` routine is available to encrypt passwords and the like.

d_csh

  From d_csh.U:

  This variable conditionally defines the `CSH` symbol, which indicates to the C program that the C-shell exists.

d_cuserid

  From d_cuserid.U:

  This variable conditionally defines the `HAS_CUSERID` symbol, which indicates to the C program that the `cuserid()` routine is available to get character login names.

d_dbl_dig

  From d_dbl_dig.U:

  This variable conditionally defines d_dbl_dig if this system's header files provide `DBL_DIG`, which is the number of significant digits in a double precision number.

d_difftime

  From d_difftime.U:

  This variable conditionally defines the `HAS_DIFFTIME` symbol, which indicates to the C program that the `difftime()` routine is available.

d_dirnamlen

  From i_dirent.U:

  This variable conditionally defines `DIRNAMLEN`, which indicates to the C program that the length of directory entry names is provided by a d_namelen field.

d_dlerror

  From d_dlerror.U:

  This variable conditionally defines the `HAS_DLERROR` symbol, which indicates to the C program that the `dlerror()` routine is available.

d_dlopen

  From d_dlopen.U:

  This variable conditionally defines the `HAS_DLOPEN` symbol, which indicates to the C program that the `dlopen()` routine is available.

d_dlsymun

  From d_dlsymun.U:

  This variable conditionally defines `DLSYM_NEEDS_UNDERSCORE`, which indicates that we need to prepend an underscore to the symbol name before calling `dlsym().`

d_dosuid

  From d_dosuid.U:

  This variable conditionally defines the symbol `DOSUID`, which tells the C program that it should insert setuid emulation code on hosts which have setuid #! scripts disabled.

d_dup2

  From d_dup2.U:

  This variable conditionally defines HAS_DUP2 if `dup2()` is available to duplicate file descriptors.

d_endgrent

  From d_endgrent.U:

  This variable conditionally defines the `HAS_ENDGRENT` symbol, which indicates to the C program that the `endgrent()` routine is available for sequential access of the group database.

d_endhent

  From d_endhent.U:

  This variable conditionally defines `HAS_ENDHOSTENT` if `endhostent()` is available to close whatever was being used for host queries.

d_endnent

  From d_endnent.U:

  This variable conditionally defines `HAS_ENDNETENT` if `endnetent()` is available to close whatever was being used for network queries.

d_endpent

  From d_endpent.U:

  This variable conditionally defines `HAS_ENDPROTOENT` if `endprotoent()` is available to close whatever was being used for protocol queries.

d_endpwent

  From d_endpwent.U:

  This variable conditionally defines the `HAS_ENDPWENT` symbol, which indicates to the C program that the `endpwent()` routine is available for sequential access of the passwd database.

d_endsent

  From d_endsent.U:

  This variable conditionally defines `HAS_ENDSERVENT` if `endservent()` is available to close whatever was being used for service queries.

d_eofnblk

  From nblock_io.U:

  This variable conditionally defines `EOF_NONBLOCK` if `EOF` can be seen when reading from a non-blocking I/O source.

d_eunice

  From Guess.U:

  This variable conditionally defines the symbols `EUNICE` and `VAX`, which alerts the C program that it must deal with ideosyncracies of VMS.

d_fchmod

  From d_fchmod.U:

  This variable conditionally defines the `HAS_FCHMOD` symbol, which indicates to the C program that the `fchmod()` routine is available to change mode of opened files.

d_fchown

  From d_fchown.U:

  This variable conditionally defines the `HAS_FCHOWN` symbol, which indicates to the C program that the `fchown()` routine is available to change ownership of opened files.

d_fcntl

  From d_fcntl.U:

  This variable conditionally defines the `HAS_FCNTL` symbol, and indicates whether the `fcntl()` function exists

d_fd_macros

  From d_fd_set.U:

  This variable contains the eventual value of the `HAS_FD_MACROS` symbol, which indicates if your C compiler knows about the macros which manipulate an fd_set.

d_fd_set

  From d_fd_set.U:

  This variable contains the eventual value of the `HAS_FD_SET` symbol, which indicates if your C compiler knows about the fd_set typedef.

d_fds_bits

  From d_fd_set.U:

  This variable contains the eventual value of the `HAS_FDS_BITS` symbol, which indicates if your fd_set typedef contains the fds_bits member. If you have an fd_set typedef, but the dweebs who installed it did a half-fast job and neglected to provide the macros to manipulate an fd_set, `HAS_FDS_BITS` will let us know how to fix the gaffe.

d_fgetpos

  From d_fgetpos.U:

  This variable conditionally defines `HAS_FGETPOS` if `fgetpos()` is available to get the file position indicator.

d_flexfnam

  From d_flexfnam.U:

  This variable conditionally defines the `FLEXFILENAMES` symbol, which indicates that the system supports filenames longer than 14 characters.

d_flock

  From d_flock.U:

  This variable conditionally defines `HAS_FLOCK` if `flock()` is available to do file locking.

d_fork

  From d_fork.U:

  This variable conditionally defines the `HAS_FORK` symbol, which indicates to the C program that the `fork()` routine is available.

d_fpathconf

  From d_pathconf.U:

  This variable conditionally defines the `HAS_FPATHCONF` symbol, which indicates to the C program that the `pathconf()` routine is available to determine file-system related limits and options associated with a given open file descriptor.

d_fsetpos

  From d_fsetpos.U:

  This variable conditionally defines `HAS_FSETPOS` if `fsetpos()` is available to set the file position indicator.

d_ftime

  From d_ftime.U:

  This variable conditionally defines the `HAS_FTIME` symbol, which indicates that the `ftime()` routine exists. The `ftime()` routine is basically a sub-second accuracy clock.

d_getgrent

  From d_getgrent.U:

  This variable conditionally defines the `HAS_GETGRENT` symbol, which indicates to the C program that the `getgrent()` routine is available for sequential access of the group database.

d_getgrps

  From d_getgrps.U:

  This variable conditionally defines the `HAS_GETGROUPS` symbol, which indicates to the C program that the `getgroups()` routine is available to get the list of process groups.

d_gethbyaddr

  From d_gethbyad.U:

  This variable conditionally defines the `HAS_GETHOSTBYADDR` symbol, which indicates to the C program that the `gethostbyaddr()` routine is available to look up hosts by their `IP` addresses.

d_gethbyname

  From d_gethbynm.U:

  This variable conditionally defines the `HAS_GETHOSTBYNAME` symbol, which indicates to the C program that the `gethostbyname()` routine is available to look up host names in some data base or other.

d_gethent

  From d_gethent.U:

  This variable conditionally defines `HAS_GETHOSTENT` if `gethostent()` is available to look up host names in some data base or another.

d_gethname

  From d_gethname.U:

  This variable conditionally defines the `HAS_GETHOSTNAME` symbol, which indicates to the C program that the `gethostname()` routine may be used to derive the host name.

d_gethostprotos

  From d_gethostprotos.U:

  This variable conditionally defines the `HAS_GETHOST_PROTOS` symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various gethost*() functions. See also netdbtype.U for probing for various netdb types.

d_getlogin

  From d_getlogin.U:

  This variable conditionally defines the `HAS_GETLOGIN` symbol, which indicates to the C program that the `getlogin()` routine is available to get the login name.

d_getnbyaddr

  From d_getnbyad.U:

  This variable conditionally defines the `HAS_GETNETBYADDR` symbol, which indicates to the C program that the `getnetbyaddr()` routine is available to look up networks by their `IP` addresses.

d_getnbyname

  From d_getnbynm.U:

  This variable conditionally defines the `HAS_GETNETBYNAME` symbol, which indicates to the C program that the `getnetbyname()` routine is available to look up networks by their names.

d_getnent

  From d_getnent.U:

  This variable conditionally defines `HAS_GETNETENT` if `getnetent()` is available to look up network names in some data base or another.

d_getnetprotos

  From d_getnetprotos.U:

  This variable conditionally defines the `HAS_GETNET_PROTOS` symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getnet*() functions. See also netdbtype.U for probing for various netdb types.

d_getpbyname

  From d_getprotby.U:

  This variable conditionally defines the `HAS_GETPROTOBYNAME` symbol, which indicates to the C program that the `getprotobyname()` routine is available to look up protocols by their name.

d_getpbynumber

  From d_getprotby.U:

  This variable conditionally defines the `HAS_GETPROTOBYNUMBER` symbol, which indicates to the C program that the `getprotobynumber()` routine is available to look up protocols by their number.

d_getpent

  From d_getpent.U:

  This variable conditionally defines `HAS_GETPROTOENT` if `getprotoent()` is available to look up protocols in some data base or another.

d_getpgid

  From d_getpgid.U:

  This variable conditionally defines the `HAS_GETPGID` symbol, which indicates to the C program that the `getpgid(pid)` function is available to get the process group id.

d_getpgrp2

  From d_getpgrp2.U:

  This variable conditionally defines the HAS_GETPGRP2 symbol, which indicates to the C program that the `getpgrp2()` (as in DG/`UX`) routine is available to get the current process group.

d_getpgrp

  From d_getpgrp.U:

  This variable conditionally defines `HAS_GETPGRP` if `getpgrp()` is available to get the current process group.

d_getppid

  From d_getppid.U:

  This variable conditionally defines the `HAS_GETPPID` symbol, which indicates to the C program that the `getppid()` routine is available to get the parent process `ID`.

d_getprior

  From d_getprior.U:

  This variable conditionally defines `HAS_GETPRIORITY` if `getpriority()` is available to get a process's priority.

d_getprotoprotos

  From d_getprotoprotos.U:

  This variable conditionally defines the `HAS_GETPROTO_PROTOS` symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getproto*() functions. See also netdbtype.U for probing for various netdb types.

d_getpwent

  From d_getpwent.U:

  This variable conditionally defines the `HAS_GETPWENT` symbol, which indicates to the C program that the `getpwent()` routine is available for sequential access of the passwd database.

d_getsbyname

  From d_getsrvby.U:

  This variable conditionally defines the `HAS_GETSERVBYNAME` symbol, which indicates to the C program that the `getservbyname()` routine is available to look up services by their name.

d_getsbyport

  From d_getsrvby.U:

  This variable conditionally defines the `HAS_GETSERVBYPORT` symbol, which indicates to the C program that the `getservbyport()` routine is available to look up services by their port.

d_getsent

  From d_getsent.U:

  This variable conditionally defines `HAS_GETSERVENT` if `getservent()` is available to look up network services in some data base or another.

d_getservprotos

  From d_getservprotos.U:

  This variable conditionally defines the `HAS_GETSERV_PROTOS` symbol, which indicates to the C program that <netdb.h> supplies prototypes for the various getserv*() functions. See also netdbtype.U for probing for various netdb types.

d_gettimeod

  From d_ftime.U:

  This variable conditionally defines the `HAS_GETTIMEOFDAY` symbol, which indicates that the `gettimeofday()` system call exists (to obtain a sub-second accuracy clock). You should probably include <sys/resource.h>.

d_gnulibc

  From d_gnulibc.U:

  Defined if we're dealing with the `GNU` C Library.

d_grpasswd

  From i_grp.U:

  This variable conditionally defines `GRPASSWD`, which indicates that struct group in <grp.h> contains gr_passwd.

d_htonl

  From d_htonl.U:

  This variable conditionally defines `HAS_HTONL` if `htonl()` and its friends are available to do network order byte swapping.

d_index

  From d_strchr.U:

  This variable conditionally defines `HAS_INDEX` if `index()` and `rindex()` are available for string searching.

d_inetaton

  From d_inetaton.U:

  This variable conditionally defines the `HAS_INET_ATON` symbol, which indicates to the C program that the `inet_aton()` function is available to parse `IP` address `dotted-quad` strings.

d_isascii

  From d_isascii.U:

  This variable conditionally defines the `HAS_ISASCII` constant, which indicates to the C program that `isascii()` is available.

d_killpg

  From d_killpg.U:

  This variable conditionally defines the `HAS_KILLPG` symbol, which indicates to the C program that the `killpg()` routine is available to kill process groups.

d_lchown

  From d_lchown.U:

  This variable conditionally defines the `HAS_LCHOWN` symbol, which indicates to the C program that the `lchown()` routine is available to operate on a symbolic link (instead of following the link).

d_link

  From d_link.U:

  This variable conditionally defines `HAS_LINK` if `link()` is available to create hard links.

d_locconv

  From d_locconv.U:

  This variable conditionally defines `HAS_LOCALECONV` if `localeconv()` is available for numeric and monetary formatting conventions.

d_lockf

  From d_lockf.U:

  This variable conditionally defines `HAS_LOCKF` if `lockf()` is available to do file locking.

d_longdbl

  From d_longdbl.U:

  This variable conditionally defines `HAS_LONG_DOUBLE` if the long double type is supported.

d_longlong

  From d_longlong.U:

  This variable conditionally defines `HAS_LONG_LONG` if the long long type is supported.

d_lstat

  From d_lstat.U:

  This variable conditionally defines `HAS_LSTAT` if `lstat()` is available to do file stats on symbolic links.

d_mblen

  From d_mblen.U:

  This variable conditionally defines the `HAS_MBLEN` symbol, which indicates to the C program that the `mblen()` routine is available to find the number of bytes in a multibye character.

d_mbstowcs

  From d_mbstowcs.U:

  This variable conditionally defines the `HAS_MBSTOWCS` symbol, which indicates to the C program that the `mbstowcs()` routine is available to convert a multibyte string into a wide character string.

d_mbtowc

  From d_mbtowc.U:

  This variable conditionally defines the `HAS_MBTOWC` symbol, which indicates to the C program that the `mbtowc()` routine is available to convert multibyte to a wide character.

d_memcmp

  From d_memcmp.U:

  This variable conditionally defines the `HAS_MEMCMP` symbol, which indicates to the C program that the `memcmp()` routine is available to compare blocks of memory.

d_memcpy

  From d_memcpy.U:

  This variable conditionally defines the `HAS_MEMCPY` symbol, which indicates to the C program that the `memcpy()` routine is available to copy blocks of memory.

d_memmove

  From d_memmove.U:

  This variable conditionally defines the `HAS_MEMMOVE` symbol, which indicates to the C program that the `memmove()` routine is available to copy potentatially overlapping blocks of memory.

d_memset

  From d_memset.U:

  This variable conditionally defines the `HAS_MEMSET` symbol, which indicates to the C program that the `memset()` routine is available to set blocks of memory.

d_mkdir

  From d_mkdir.U:

  This variable conditionally defines the `HAS_MKDIR` symbol, which indicates to the C program that the `mkdir()` routine is available to create directories..

d_mkfifo

  From d_mkfifo.U:

  This variable conditionally defines the `HAS_MKFIFO` symbol, which indicates to the C program that the `mkfifo()` routine is available.

d_mktime

  From d_mktime.U:

  This variable conditionally defines the `HAS_MKTIME` symbol, which indicates to the C program that the `mktime()` routine is available.

d_msg

  From d_msg.U:

  This variable conditionally defines the `HAS_MSG` symbol, which indicates that the entire msg*(2) library is present.

d_msgctl

  From d_msgctl.U:

  This variable conditionally defines the `HAS_MSGCTL` symbol, which indicates to the C program that the `msgctl()` routine is available.

d_msgget

  From d_msgget.U:

  This variable conditionally defines the `HAS_MSGGET` symbol, which indicates to the C program that the `msgget()` routine is available.

d_msgrcv

  From d_msgrcv.U:

  This variable conditionally defines the `HAS_MSGRCV` symbol, which indicates to the C program that the `msgrcv()` routine is available.

d_msgsnd

  From d_msgsnd.U:

  This variable conditionally defines the `HAS_MSGSND` symbol, which indicates to the C program that the `msgsnd()` routine is available.

d_mymalloc

  From mallocsrc.U:

  This variable conditionally defines `MYMALLOC` in case other parts of the source want to take special action if `MYMALLOC` is used. This may include different sorts of profiling or error detection.

d_nice

  From d_nice.U:

  This variable conditionally defines the `HAS_NICE` symbol, which indicates to the C program that the `nice()` routine is available.

d_oldpthreads

  From usethreads.U:

  This variable conditionally defines the `OLD_PTHREADS_API` symbol, and indicates that Perl should be built to use the old draft POSIX threads API. This is only potneially meaningful if usethreads is set.

d_oldsock

  From d_socket.U:

  This variable conditionally defines the `OLDSOCKET` symbol, which indicates that the `BSD` socket interface is based on 4.1c and not 4.2.

d_open3

  From d_open3.U:

  This variable conditionally defines the HAS_OPEN3 manifest constant, which indicates to the C program that the 3 argument version of the `open(2)` function is available.

d_pathconf

  From d_pathconf.U:

  This variable conditionally defines the `HAS_PATHCONF` symbol, which indicates to the C program that the `pathconf()` routine is available to determine file-system related limits and options associated with a given filename.

d_pause

  From d_pause.U:

  This variable conditionally defines the `HAS_PAUSE` symbol, which indicates to the C program that the `pause()` routine is available to suspend a process until a signal is received.

d_phostname

  From d_gethname.U:

  This variable conditionally defines the `PHOSTNAME` symbol, which contains the shell command which, when fed to `popen(),` may be used to derive the host name.

d_pipe

  From d_pipe.U:

  This variable conditionally defines the `HAS_PIPE` symbol, which indicates to the C program that the `pipe()` routine is available to create an inter-process channel.

d_poll

  From d_poll.U:

  This variable conditionally defines the `HAS_POLL` symbol, which indicates to the C program that the `poll()` routine is available to poll active file descriptors.

d_portable

  From d_portable.U:

  This variable conditionally defines the `PORTABLE` symbol, which indicates to the C program that it should not assume that it is running on the machine it was compiled on.

d_pthread_yield

  From d_pthread_y.U:

  This variable conditionally defines the `HAS_PTHREAD_YIELD` symbol if the pthread_yield routine is available to yield the execution of the current thread.

d_pthreads_created_joinable

  From d_pthreadj.U:

  This variable conditionally defines the `PTHREADS_CREATED_JOINABLE` symbol if pthreads are created in the joinable (aka undetached) state.

d_pwage

  From i_pwd.U:

  This variable conditionally defines `PWAGE`, which indicates that struct passwd contains pw_age.

d_pwchange

  From i_pwd.U:

  This variable conditionally defines `PWCHANGE`, which indicates that struct passwd contains pw_change.

d_pwclass

  From i_pwd.U:

  This variable conditionally defines `PWCLASS`, which indicates that struct passwd contains pw_class.

d_pwcomment

  From i_pwd.U:

  This variable conditionally defines `PWCOMMENT`, which indicates that struct passwd contains pw_comment.

d_pwexpire

  From i_pwd.U:

  This variable conditionally defines `PWEXPIRE`, which indicates that struct passwd contains pw_expire.

d_pwgecos

  From i_pwd.U:

  This variable conditionally defines `PWGECOS`, which indicates that struct passwd contains pw_gecos.

d_pwpasswd

  From i_pwd.U:

  This variable conditionally defines `PWPASSWD`, which indicates that struct passwd contains pw_passwd.

d_pwquota

  From i_pwd.U:

  This variable conditionally defines `PWQUOTA`, which indicates that struct passwd contains pw_quota.

d_readdir

  From d_readdir.U:

  This variable conditionally defines `HAS_READDIR` if `readdir()` is available to read directory entries.

d_readlink

  From d_readlink.U:

  This variable conditionally defines the `HAS_READLINK` symbol, which indicates to the C program that the `readlink()` routine is available to read the value of a symbolic link.

d_rename

  From d_rename.U:

  This variable conditionally defines the `HAS_RENAME` symbol, which indicates to the C program that the `rename()` routine is available to rename files.

d_rewinddir

  From d_readdir.U:

  This variable conditionally defines `HAS_REWINDDIR` if `rewinddir()` is available.

d_rmdir

  From d_rmdir.U:

  This variable conditionally defines `HAS_RMDIR` if `rmdir()` is available to remove directories.

d_safebcpy

  From d_safebcpy.U:

  This variable conditionally defines the `HAS_SAFE_BCOPY` symbol if the `bcopy()` routine can do overlapping copies.

d_safemcpy

  From d_safemcpy.U:

  This variable conditionally defines the `HAS_SAFE_MEMCPY` symbol if the `memcpy()` routine can do overlapping copies.

d_sanemcmp

  From d_sanemcmp.U:

  This variable conditionally defines the `HAS_SANE_MEMCMP` symbol if the `memcpy()` routine is available and can be used to compare relative magnitudes of chars with their high bits set.

d_sched_yield

  From d_pthread_y.U:

  This variable conditionally defines the `HAS_SCHED_YIELD` symbol if the sched_yield routine is available to yield the execution of the current thread.

d_seekdir

  From d_readdir.U:

  This variable conditionally defines `HAS_SEEKDIR` if `seekdir()` is available.

d_select

  From d_select.U:

  This variable conditionally defines `HAS_SELECT` if `select()` is available to select active file descriptors. A <sys/time.h> inclusion may be necessary for the timeout field.

d_sem

  From d_sem.U:

  This variable conditionally defines the `HAS_SEM` symbol, which indicates that the entire sem*(2) library is present.

d_semctl

  From d_semctl.U:

  This variable conditionally defines the `HAS_SEMCTL` symbol, which indicates to the C program that the `semctl()` routine is available.

d_semctl_semid_ds

  From d_union_senum.U:

  This variable conditionally defines `USE_SEMCTL_SEMID_DS`, which indicates that struct semid_ds * is to be used for semctl `IPC_STAT`.

d_semctl_semun

  From d_union_senum.U:

  This variable conditionally defines `USE_SEMCTL_SEMUN`, which indicates that union semun is to be used for semctl `IPC_STAT`.

d_semget

  From d_semget.U:

  This variable conditionally defines the `HAS_SEMGET` symbol, which indicates to the C program that the `semget()` routine is available.

d_semop

  From d_semop.U:

  This variable conditionally defines the `HAS_SEMOP` symbol, which indicates to the C program that the `semop()` routine is available.

d_setegid

  From d_setegid.U:

  This variable conditionally defines the `HAS_SETEGID` symbol, which indicates to the C program that the `setegid()` routine is available to change the effective gid of the current program.

d_seteuid

  From d_seteuid.U:

  This variable conditionally defines the `HAS_SETEUID` symbol, which indicates to the C program that the `seteuid()` routine is available to change the effective uid of the current program.

d_setgrent

  From d_setgrent.U:

  This variable conditionally defines the `HAS_SETGRENT` symbol, which indicates to the C program that the `setgrent()` routine is available for initializing sequential access to the group database.

d_setgrps

  From d_setgrps.U:

  This variable conditionally defines the `HAS_SETGROUPS` symbol, which indicates to the C program that the `setgroups()` routine is available to set the list of process groups.

d_sethent

  From d_sethent.U:

  This variable conditionally defines `HAS_SETHOSTENT` if `sethostent()` is available.

d_setlinebuf

  From d_setlnbuf.U:

  This variable conditionally defines the `HAS_SETLINEBUF` symbol, which indicates to the C program that the `setlinebuf()` routine is available to change stderr or stdout from block-buffered or unbuffered to a line-buffered mode.

d_setlocale

  From d_setlocale.U:

  This variable conditionally defines `HAS_SETLOCALE` if `setlocale()` is available to handle locale-specific ctype implementations.

d_setnent

  From d_setnent.U:

  This variable conditionally defines `HAS_SETNETENT` if `setnetent()` is available.

d_setpent

  From d_setpent.U:

  This variable conditionally defines `HAS_SETPROTOENT` if `setprotoent()` is available.

d_setpgid

  From d_setpgid.U:

  This variable conditionally defines the `HAS_SETPGID` symbol if the `setpgid(pid,` gpid) function is available to set process group `ID`.

d_setpgrp2

  From d_setpgrp2.U:

  This variable conditionally defines the HAS_SETPGRP2 symbol, which indicates to the C program that the `setpgrp2()` (as in DG/`UX`) routine is available to set the current process group.

d_setpgrp

  From d_setpgrp.U:

  This variable conditionally defines `HAS_SETPGRP` if `setpgrp()` is available to set the current process group.

d_setprior

  From d_setprior.U:

  This variable conditionally defines `HAS_SETPRIORITY` if `setpriority()` is available to set a process's priority.

d_setpwent

  From d_setpwent.U:

  This variable conditionally defines the `HAS_SETPWENT` symbol, which indicates to the C program that the `setpwent()` routine is available for initializing sequential access to the passwd database.

d_setregid

  From d_setregid.U:

  This variable conditionally defines `HAS_SETREGID` if `setregid()` is available to change the real and effective gid of the current process.

d_setresgid

  From d_setregid.U:

  This variable conditionally defines `HAS_SETRESGID` if `setresgid()` is available to change the real, effective and saved gid of the current process.

d_setresuid

  From d_setreuid.U:

  This variable conditionally defines `HAS_SETREUID` if `setresuid()` is available to change the real, effective and saved uid of the current process.

d_setreuid

  From d_setreuid.U:

  This variable conditionally defines `HAS_SETREUID` if `setreuid()` is available to change the real and effective uid of the current process.

d_setrgid

  From d_setrgid.U:

  This variable conditionally defines the `HAS_SETRGID` symbol, which indicates to the C program that the `setrgid()` routine is available to change the real gid of the current program.

d_setruid

  From d_setruid.U:

  This variable conditionally defines the `HAS_SETRUID` symbol, which indicates to the C program that the `setruid()` routine is available to change the real uid of the current program.

d_setsent

  From d_setsent.U:

  This variable conditionally defines `HAS_SETSERVENT` if `setservent()` is available.

d_setsid

  From d_setsid.U:

  This variable conditionally defines `HAS_SETSID` if `setsid()` is available to set the process group `ID`.

d_setvbuf

  From d_setvbuf.U:

  This variable conditionally defines the `HAS_SETVBUF` symbol, which indicates to the C program that the `setvbuf()` routine is available to change buffering on an open stdio stream.

d_sfio

  From d_sfio.U:

  This variable conditionally defines the `USE_SFIO` symbol, and indicates whether sfio is available (and should be used).

d_shm

  From d_shm.U:

  This variable conditionally defines the `HAS_SHM` symbol, which indicates that the entire shm*(2) library is present.

d_shmat

  From d_shmat.U:

  This variable conditionally defines the `HAS_SHMAT` symbol, which indicates to the C program that the `shmat()` routine is available.

d_shmatprototype

  From d_shmat.U:

  This variable conditionally defines the `HAS_SHMAT_PROTOTYPE` symbol, which indicates that sys/shm.h has a prototype for shmat.

d_shmctl

  From d_shmctl.U:

  This variable conditionally defines the `HAS_SHMCTL` symbol, which indicates to the C program that the `shmctl()` routine is available.

d_shmdt

  From d_shmdt.U:

  This variable conditionally defines the `HAS_SHMDT` symbol, which indicates to the C program that the `shmdt()` routine is available.

d_shmget

  From d_shmget.U:

  This variable conditionally defines the `HAS_SHMGET` symbol, which indicates to the C program that the `shmget()` routine is available.

d_sigaction

  From d_sigaction.U:

  This variable conditionally defines the `HAS_SIGACTION` symbol, which indicates that the Vr4 `sigaction()` routine is available.

d_sigsetjmp

  From d_sigsetjmp.U:

  This variable conditionally defines the `HAS_SIGSETJMP` symbol, which indicates that the `sigsetjmp()` routine is available to call `setjmp()` and optionally save the process's signal mask.

d_socket

  From d_socket.U:

  This variable conditionally defines `HAS_SOCKET`, which indicates that the `BSD` socket interface is supported.

d_sockpair

  From d_socket.U:

  This variable conditionally defines the `HAS_SOCKETPAIR` symbol, which indicates that the `BSD` `socketpair()` is supported.

d_statblks

  From d_statblks.U:

  This variable conditionally defines `USE_STAT_BLOCKS` if this system has a stat structure declaring st_blksize and st_blocks.

d_stdio_cnt_lval

  From d_stdstdio.U:

  This variable conditionally defines `STDIO_CNT_LVALUE` if the `FILE_cnt` macro can be used as an lvalue.

d_stdio_ptr_lval

  From d_stdstdio.U:

  This variable conditionally defines `STDIO_PTR_LVALUE` if the `FILE_ptr` macro can be used as an lvalue.

d_stdiobase

  From d_stdstdio.U:

  This variable conditionally defines `USE_STDIO_BASE` if this system has a FILE structure declaring a usable _base field (or equivalent) in stdio.h.

d_stdstdio

  From d_stdstdio.U:

  This variable conditionally defines `USE_STDIO_PTR` if this system has a FILE structure declaring usable _ptr and _cnt fields (or equivalent) in stdio.h.

d_strchr

  From d_strchr.U:

  This variable conditionally defines `HAS_STRCHR` if `strchr()` and `strrchr()` are available for string searching.

d_strcoll

  From d_strcoll.U:

  This variable conditionally defines `HAS_STRCOLL` if `strcoll()` is available to compare strings using collating information.

d_strctcpy

  From d_strctcpy.U:

  This variable conditionally defines the `USE_STRUCT_COPY` symbol, which indicates to the C program that this C compiler knows how to copy structures.

d_strerrm

  From d_strerror.U:

  This variable holds what Strerrr is defined as to translate an error code condition into an error message string. It could be strerror or a more `complex` macro emulating strrror with sys_errlist[], or the `unknown` string when both strerror and sys_errlist are missing.

d_strerror

  From d_strerror.U:

  This variable conditionally defines `HAS_STRERROR` if `strerror()` is available to translate error numbers to strings.

d_strtod

  From d_strtod.U:

  This variable conditionally defines the `HAS_STRTOD` symbol, which indicates to the C program that the `strtod()` routine is available to provide better numeric string conversion than `atof().`

d_strtol

  From d_strtol.U:

  This variable conditionally defines the `HAS_STRTOL` symbol, which indicates to the C program that the `strtol()` routine is available to provide better numeric string conversion than `atoi()` and friends.

d_strtoul

  From d_strtoul.U:

  This variable conditionally defines the `HAS_STRTOUL` symbol, which indicates to the C program that the `strtoul()` routine is available to provide conversion of strings to unsigned long.

d_strxfrm

  From d_strxfrm.U:

  This variable conditionally defines `HAS_STRXFRM` if `strxfrm()` is available to transform strings.

d_suidsafe

  From d_dosuid.U:

  This variable conditionally defines `SETUID_SCRIPTS_ARE_SECURE_NOW` if setuid scripts can be secure. This test looks in /dev/fd/.

d_symlink

  From d_symlink.U:

  This variable conditionally defines the `HAS_SYMLINK` symbol, which indicates to the C program that the `symlink()` routine is available to create symbolic links.

d_syscall

  From d_syscall.U:

  This variable conditionally defines `HAS_SYSCALL` if `syscall()` is available call arbitrary system calls.

d_sysconf

  From d_sysconf.U:

  This variable conditionally defines the `HAS_SYSCONF` symbol, which indicates to the C program that the `sysconf()` routine is available to determine system related limits and options.

d_sysernlst

  From d_strerror.U:

  This variable conditionally defines `HAS_SYS_ERRNOLIST` if sys_errnolist[] is available to translate error numbers to the symbolic name.

d_syserrlst

  From d_strerror.U:

  This variable conditionally defines `HAS_SYS_ERRLIST` if sys_errlist[] is available to translate error numbers to strings.

d_system

  From d_system.U:

  This variable conditionally defines `HAS_SYSTEM` if `system()` is available to issue a shell command.

d_tcgetpgrp

  From d_tcgtpgrp.U:

  This variable conditionally defines the `HAS_TCGETPGRP` symbol, which indicates to the C program that the `tcgetpgrp()` routine is available. to get foreground process group `ID`.

d_tcsetpgrp

  From d_tcstpgrp.U:

  This variable conditionally defines the `HAS_TCSETPGRP` symbol, which indicates to the C program that the `tcsetpgrp()` routine is available to set foreground process group `ID`.

d_telldir

  From d_readdir.U:

  This variable conditionally defines `HAS_TELLDIR` if `telldir()` is available.

d_time

  From d_time.U:

  This variable conditionally defines the `HAS_TIME` symbol, which indicates that the `time()` routine exists. The `time()` routine is normaly provided on `UNIX` systems.

d_times

  From d_times.U:

  This variable conditionally defines the `HAS_TIMES` symbol, which indicates that the `times()` routine exists. The `times()` routine is normaly provided on `UNIX` systems. You may have to include <sys/times.h>.

d_truncate

  From d_truncate.U:

  This variable conditionally defines `HAS_TRUNCATE` if `truncate()` is available to truncate files.

d_tzname

  From d_tzname.U:

  This variable conditionally defines `HAS_TZNAME` if tzname[] is available to access timezone names.

d_umask

  From d_umask.U:

  This variable conditionally defines the `HAS_UMASK` symbol, which indicates to the C program that the `umask()` routine is available. to set and get the value of the file creation mask.

d_uname

  From d_gethname.U:

  This variable conditionally defines the `HAS_UNAME` symbol, which indicates to the C program that the `uname()` routine may be used to derive the host name.

d_union_semun

  From d_union_senum.U:

  This variable conditionally defines `HAS_UNION_SEMUN` if the union semun is defined by including <sys/sem.h>.

d_vfork

  From d_vfork.U:

  This variable conditionally defines the `HAS_VFORK` symbol, which indicates the `vfork()` routine is available.

d_void_closedir

  From d_closedir.U:

  This variable conditionally defines `VOID_CLOSEDIR` if `closedir()` does not return a value.

d_voidsig

  From d_voidsig.U:

  This variable conditionally defines `VOIDSIG` if this system declares ``void (*signal(...))()'' in signal.h. The old way was to declare it as ``int (*signal(...))()''.

d_voidtty

  From i_sysioctl.U:

  This variable conditionally defines `USE_IOCNOTTY` to indicate that the `ioctl()` call with `TIOCNOTTY` should be used to void tty association. Otherwise (on `USG` probably), it is enough to close the standard file decriptors and do a `setpgrp().`

d_volatile

  From d_volatile.U:

  This variable conditionally defines the `HASVOLATILE` symbol, which indicates to the C program that this C compiler knows about the volatile declaration.

d_vprintf

  From d_vprintf.U:

  This variable conditionally defines the `HAS_VPRINTF` symbol, which indicates to the C program that the `vprintf()` routine is available to printf with a pointer to an argument list.

d_wait4

  From d_wait4.U:

  This variable conditionally defines the HAS_WAIT4 symbol, which indicates the `wait4()` routine is available.

d_waitpid

  From d_waitpid.U:

  This variable conditionally defines `HAS_WAITPID` if `waitpid()` is available to wait for child process.

d_wcstombs

  From d_wcstombs.U:

  This variable conditionally defines the `HAS_WCSTOMBS` symbol, which indicates to the C program that the `wcstombs()` routine is available to convert wide character strings to multibyte strings.

d_wctomb

  From d_wctomb.U:

  This variable conditionally defines the `HAS_WCTOMB` symbol, which indicates to the C program that the `wctomb()` routine is available to convert a wide character to a multibyte.

d_xenix

  From Guess.U:

  This variable conditionally defines the symbol `XENIX`, which alerts the C program that it runs under Xenix.

date

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the date program. After Configure runs, the value is reset to a plain date and is not useful.

db_hashtype

  From i_db.U:

  This variable contains the type of the hash structure element in the <db.h> header file. In older versions of `DB`, it was int, while in newer ones it is u_int32_t.

db_prefixtype

  From i_db.U:

  This variable contains the type of the prefix structure element in the <db.h> header file. In older versions of `DB`, it was int, while in newer ones it is size_t.

direntrytype

  From i_dirent.U:

  This symbol is set to `struct direct` or `struct dirent` depending on whether dirent is available or not. You should use this pseudo type to portably declare your directory entries.

dlext

  From dlext.U:

  This variable contains the extension that is to be used for the dynamically loaded modules that perl generaties.

dlsrc

  From dlsrc.U:

  This variable contains the name of the dynamic loading file that will be used with the package.

doublesize

  From doublesize.U:

  This variable contains the value of the `DOUBLESIZE` symbol, which indicates to the C program how many bytes there are in a double.

dynamic_ext

  From Extensions.U:

  This variable holds a list of XS extension files we want to link dynamically into the package. It is used by Makefile.

## e

eagain

  From nblock_io.U:

  This variable bears the symbolic errno code set by `read()` when no data is present on the file and non-blocking I/O was enabled (otherwise, `read()` blocks naturally).

ebcdic

  From ebcdic.U:

  This variable conditionally defines EBCDIC if this system uses EBCDIC encoding. Among other things, this means that the character ranges are not contiguous. See trnl.U

echo

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the echo program. After Configure runs, the value is reset to a plain echo and is not useful.

egrep

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the egrep program. After Configure runs, the value is reset to a plain egrep and is not useful.

emacs

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

eunicefix

  From Init.U:

  When running under Eunice this variable contains a command which will convert a shell script to the proper form of text file for it to be executable by the shell. On other systems it is a no-op.

exe_ext

  From Unix.U:

  This is an old synonym for _exe.

expr

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the expr program. After Configure runs, the value is reset to a plain expr and is not useful.

extensions

  From Extensions.U:

  This variable holds a list of all extension files (both XS and non-xs linked into the package. It is propagated to Config.pm and is typically used to test whether a particular extesion is available.

## f

find

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the find program. After Configure runs, the value is reset to a plain find and is not useful.

firstmakefile

  From Unix.U:

  This variable defines the first file searched by make. On unix, it is makefile (then Makefile). On case-insensitive systems, it might be something else. This is only used to deal with convoluted make depend tricks.

flex

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

fpostype

  From fpostype.U:

  This variable defines Fpos_t to be something like fpost_t, long, uint, or whatever type is used to declare file positions in libc.

freetype

  From mallocsrc.U:

  This variable contains the return type of `free().` It is usually void, but occasionally int.

full_csh

  From d_csh.U:

  This variable contains the full pathname to csh, whether or not the user has specified `portability`. This is only used in the compiled C program, and we assume that all systems which can share this executable will have the same full pathname to csh.

full_sed

  From Loc_sed.U:

  This variable contains the full pathname to sed, whether or not the user has specified `portability`. This is only used in the compiled C program, and we assume that all systems which can share this executable will have the same full pathname to sed.

## g

gccversion

  From cc.U:

  If `GNU` cc (gcc) is used, this variable holds `1` or `2` to indicate whether the compiler is version 1 or 2. This is used in setting some of the default cflags. It is set to '' if not gcc.

gidtype

  From gidtype.U:

  This variable defines Gid_t to be something like gid_t, int, ushort, or whatever type is used to declare the return type of `getgid().` Typically, it is the type of group ids in the kernel.

grep

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the grep program. After Configure runs, the value is reset to a plain grep and is not useful.

groupcat

  From nis.U:

  This variable contains a command that produces the text of the /etc/group file. This is normally ``cat /etc/group'', but can be ``ypcat group'' when `NIS` is used.

groupstype

  From groupstype.U:

  This variable defines Groups_t to be something like gid_t, int, ushort, or whatever type is used for the second argument to `getgroups()` and `setgroups().` Usually, this is the same as gidtype (gid_t), but sometimes it isn't.

gzip

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the gzip program. After Configure runs, the value is reset to a plain gzip and is not useful.

## h

h_fcntl

  From h_fcntl.U:

  This is variable gets set in various places to tell i_fcntl that <fcntl.h> should be included.

h_sysfile

  From h_sysfile.U:

  This is variable gets set in various places to tell i_sys_file that <sys/file.h> should be included.

hint

  From Oldconfig.U:

  Gives the type of hints used for previous answers. May be one of default, `recommended` or `previous`.

hostcat

  From nis.U:

  This variable contains a command that produces the text of the /etc/hosts file. This is normally ``cat /etc/hosts'', but can be ``ypcat hosts'' when `NIS` is used.

huge

  From models.U:

  This variable contains a flag which will tell the C compiler and loader to produce a program running with a huge memory model. If the huge model is not supported, contains the flag to produce large model programs. It is up to the Makefile to use this.

## i

i_arpainet

  From i_arpainet.U:

  This variable conditionally defines the `I_ARPA_INET` symbol, and indicates whether a C program should include <arpa/inet.h>.

i_bsdioctl

  From i_sysioctl.U:

  This variable conditionally defines the `I_SYS_BSDIOCTL` symbol, which indicates to the C program that <sys/bsdioctl.h> exists and should be included.

i_db

  From i_db.U:

  This variable conditionally defines the `I_DB` symbol, and indicates whether a C program may include Berkeley's `DB` include file <db.h>.

i_dbm

  From i_dbm.U:

  This variable conditionally defines the `I_DBM` symbol, which indicates to the C program that <dbm.h> exists and should be included.

i_dirent

  From i_dirent.U:

  This variable conditionally defines `I_DIRENT`, which indicates to the C program that it should include <dirent.h>.

i_dld

  From i_dld.U:

  This variable conditionally defines the `I_DLD` symbol, which indicates to the C program that <dld.h> (`GNU` dynamic loading) exists and should be included.

i_dlfcn

  From i_dlfcn.U:

  This variable conditionally defines the `I_DLFCN` symbol, which indicates to the C program that <dlfcn.h> exists and should be included.

i_fcntl

  From i_fcntl.U:

  This variable controls the value of `I_FCNTL` (which tells the C program to include <fcntl.h>).

i_float

  From i_float.U:

  This variable conditionally defines the `I_FLOAT` symbol, and indicates whether a C program may include <float.h> to get symbols like `DBL_MAX` or `DBL_MIN`, i.e. machine dependent floating point values.

i_gdbm

  From i_gdbm.U:

  This variable conditionally defines the `I_GDBM` symbol, which indicates to the C program that <gdbm.h> exists and should be included.

i_grp

  From i_grp.U:

  This variable conditionally defines the `I_GRP` symbol, and indicates whether a C program should include <grp.h>.

i_limits

  From i_limits.U:

  This variable conditionally defines the `I_LIMITS` symbol, and indicates whether a C program may include <limits.h> to get symbols like `WORD_BIT` and friends.

i_locale

  From i_locale.U:

  This variable conditionally defines the `I_LOCALE` symbol, and indicates whether a C program should include <locale.h>.

i_malloc

  From i_malloc.U:

  This variable conditionally defines the `I_MALLOC` symbol, and indicates whether a C program should include <malloc.h>.

i_math

  From i_math.U:

  This variable conditionally defines the `I_MATH` symbol, and indicates whether a C program may include <math.h>.

i_memory

  From i_memory.U:

  This variable conditionally defines the `I_MEMORY` symbol, and indicates whether a C program should include <memory.h>.

i_ndbm

  From i_ndbm.U:

  This variable conditionally defines the `I_NDBM` symbol, which indicates to the C program that <ndbm.h> exists and should be included.

i_netdb

  From i_netdb.U:

  This variable conditionally defines the `I_NETDB` symbol, and indicates whether a C program should include <netdb.h>.

i_neterrno

  From i_neterrno.U:

  This variable conditionally defines the `I_NET_ERRNO` symbol, which indicates to the C program that <net/errno.h> exists and should be included.

i_niin

  From i_niin.U:

  This variable conditionally defines `I_NETINET_IN`, which indicates to the C program that it should include <netinet/in.h>. Otherwise, you may try <sys/in.h>.

i_pwd

  From i_pwd.U:

  This variable conditionally defines `I_PWD`, which indicates to the C program that it should include <pwd.h>.

i_rpcsvcdbm

  From i_dbm.U:

  This variable conditionally defines the `I_RPCSVC_DBM` symbol, which indicates to the C program that <rpcsvc/dbm.h> exists and should be included. Some System V systems might need this instead of <dbm.h>.

i_sfio

  From i_sfio.U:

  This variable conditionally defines the `I_SFIO` symbol, and indicates whether a C program should include <sfio.h>.

i_sgtty

  From i_termio.U:

  This variable conditionally defines the `I_SGTTY` symbol, which indicates to the C program that it should include <sgtty.h> rather than <termio.h>.

i_stdarg

  From i_varhdr.U:

  This variable conditionally defines the `I_STDARG` symbol, which indicates to the C program that <stdarg.h> exists and should be included.

i_stddef

  From i_stddef.U:

  This variable conditionally defines the `I_STDDEF` symbol, which indicates to the C program that <stddef.h> exists and should be included.

i_stdlib

  From i_stdlib.U:

  This variable conditionally defines the `I_STDLIB` symbol, which indicates to the C program that <stdlib.h> exists and should be included.

i_string

  From i_string.U:

  This variable conditionally defines the `I_STRING` symbol, which indicates that <string.h> should be included rather than <strings.h>.

i_sysdir

  From i_sysdir.U:

  This variable conditionally defines the `I_SYS_DIR` symbol, and indicates whether a C program should include <sys/dir.h>.

i_sysfile

  From i_sysfile.U:

  This variable conditionally defines the `I_SYS_FILE` symbol, and indicates whether a C program should include <sys/file.h> to get `R_OK` and friends.

i_sysfilio

  From i_sysioctl.U:

  This variable conditionally defines the `I_SYS_FILIO` symbol, which indicates to the C program that <sys/filio.h> exists and should be included in preference to <sys/ioctl.h>.

i_sysin

  From i_niin.U:

  This variable conditionally defines `I_SYS_IN`, which indicates to the C program that it should include <sys/in.h> instead of <netinet/in.h>.

i_sysioctl

  From i_sysioctl.U:

  This variable conditionally defines the `I_SYS_IOCTL` symbol, which indicates to the C program that <sys/ioctl.h> exists and should be included.

i_sysndir

  From i_sysndir.U:

  This variable conditionally defines the `I_SYS_NDIR` symbol, and indicates whether a C program should include <sys/ndir.h>.

i_sysparam

  From i_sysparam.U:

  This variable conditionally defines the `I_SYS_PARAM` symbol, and indicates whether a C program should include <sys/param.h>.

i_sysresrc

  From i_sysresrc.U:

  This variable conditionally defines the `I_SYS_RESOURCE` symbol, and indicates whether a C program should include <sys/resource.h>.

i_sysselct

  From i_sysselct.U:

  This variable conditionally defines `I_SYS_SELECT`, which indicates to the C program that it should include <sys/select.h> in order to get the definition of struct timeval.

i_syssockio

  From i_sysioctl.U:

  This variable conditionally defines `I_SYS_SOCKIO` to indicate to the C program that socket ioctl codes may be found in <sys/sockio.h> instead of <sys/ioctl.h>.

i_sysstat

  From i_sysstat.U:

  This variable conditionally defines the `I_SYS_STAT` symbol, and indicates whether a C program should include <sys/stat.h>.

i_systime

  From i_time.U:

  This variable conditionally defines `I_SYS_TIME`, which indicates to the C program that it should include <sys/time.h>.

i_systimek

  From i_time.U:

  This variable conditionally defines `I_SYS_TIME_KERNEL`, which indicates to the C program that it should include <sys/time.h> with `KERNEL` defined.

i_systimes

  From i_systimes.U:

  This variable conditionally defines the `I_SYS_TIMES` symbol, and indicates whether a C program should include <sys/times.h>.

i_systypes

  From i_systypes.U:

  This variable conditionally defines the `I_SYS_TYPES` symbol, and indicates whether a C program should include <sys/types.h>.

i_sysun

  From i_sysun.U:

  This variable conditionally defines `I_SYS_UN`, which indicates to the C program that it should include <sys/un.h> to get `UNIX` domain socket definitions.

i_syswait

  From i_syswait.U:

  This variable conditionally defines `I_SYS_WAIT`, which indicates to the C program that it should include <sys/wait.h>.

i_termio

  From i_termio.U:

  This variable conditionally defines the `I_TERMIO` symbol, which indicates to the C program that it should include <termio.h> rather than <sgtty.h>.

i_termios

  From i_termio.U:

  This variable conditionally defines the `I_TERMIOS` symbol, which indicates to the C program that the POSIX <termios.h> file is to be included.

i_time

  From i_time.U:

  This variable conditionally defines `I_TIME`, which indicates to the C program that it should include <time.h>.

i_unistd

  From i_unistd.U:

  This variable conditionally defines the `I_UNISTD` symbol, and indicates whether a C program should include <unistd.h>.

i_utime

  From i_utime.U:

  This variable conditionally defines the `I_UTIME` symbol, and indicates whether a C program should include <utime.h>.

i_values

  From i_values.U:

  This variable conditionally defines the `I_VALUES` symbol, and indicates whether a C program may include <values.h> to get symbols like `MAXLONG` and friends.

i_varargs

  From i_varhdr.U:

  This variable conditionally defines `I_VARARGS`, which indicates to the C program that it should include <varargs.h>.

i_varhdr

  From i_varhdr.U:

  Contains the name of the header to be included to get va_dcl definition. Typically one of varargs.h or stdarg.h.

i_vfork

  From i_vfork.U:

  This variable conditionally defines the `I_VFORK` symbol, and indicates whether a C program should include vfork.h.

incpath

  From usrinc.U:

  This variable must preceed the normal include path to get hte right one, as in $incpath/usr/include or $incpath/usr/lib. Value can be ``'' or /bsd43 on mips.

inews

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

installarchlib

  From archlib.U:

  This variable is really the same as archlibexp but may differ on those systems using AFS. For extra portability, only this variable should be used in makefiles.

installbin

  From bin.U:

  This variable is the same as binexp unless AFS is running in which case the user is explicitely prompted for it. This variable should always be used in your makefiles for maximum portability.

installman1dir

  From man1dir.U:

  This variable is really the same as man1direxp, unless you are using AFS in which case it points to the read/write location whereas man1direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

installman3dir

  From man3dir.U:

  This variable is really the same as man3direxp, unless you are using AFS in which case it points to the read/write location whereas man3direxp only points to the read-only access location. For extra portability, you should only use this variable within your makefiles.

installprivlib

  From privlib.U:

  This variable is really the same as privlibexp but may differ on those systems using AFS. For extra portability, only this variable should be used in makefiles.

installscript

  From scriptdir.U:

  This variable is usually the same as scriptdirexp, unless you are on a system running AFS, in which case they may differ slightly. You should always use this variable within your makefiles for portability.

installsitearch

  From sitearch.U:

  This variable is really the same as sitearchexp but may differ on those systems using AFS. For extra portability, only this variable should be used in makefiles.

installsitelib

  From sitelib.U:

  This variable is really the same as sitelibexp but may differ on those systems using AFS. For extra portability, only this variable should be used in makefiles.

intsize

  From intsize.U:

  This variable contains the value of the `INTSIZE` symbol, which indicates to the C program how many bytes there are in an int.

## k

known_extensions

  From Extensions.U:

  This variable holds a list of all XS extensions included in the package.

ksh

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

## l

large

  From models.U:

  This variable contains a flag which will tell the C compiler and loader to produce a program running with a large memory model. It is up to the Makefile to use this.

ld

  From dlsrc.U:

  This variable indicates the program to be used to link libraries for dynamic loading. On some systems, it is ld. On `ELF` systems, it should be $cc. Mostly, we'll try to respect the hint file setting.

lddlflags

  From dlsrc.U:

  This variable contains any special flags that might need to be passed to $ld to create a shared library suitable for dynamic loading. It is up to the makefile to use it. For hpux, it should be -b. For sunos 4.1, it is empty.

ldflags

  From ccflags.U:

  This variable contains any additional C loader flags desired by the user. It is up to the Makefile to use this.

less

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the less program. After Configure runs, the value is reset to a plain less and is not useful.

lib_ext

  From Unix.U:

  This is an old synonym for _a.

libc

  From libc.U:

  This variable contains the location of the C library.

libperl

  From libperl.U:

  The perl executable is obtained by linking perlmain.c with libperl, any static extensions (usually just DynaLoader), and any other libraries needed on this system. libperl is usually libperl.a, but can also be libperl.so.xxx if the user wishes to build a perl executable with a shared library.

libpth

  From libpth.U:

  This variable holds the general path used to find libraries. It is intended to be used by other units.

libs

  From libs.U:

  This variable holds the additional libraries we want to use. It is up to the Makefile to deal with it.

libswanted

  From Myinit.U:

  This variable holds a list of all the libraries we want to search. The order is chosen to pick up the c library ahead of ucb or bsd libraries for SVR4.

line

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the line program. After Configure runs, the value is reset to a plain line and is not useful.

lint

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

lkflags

  From ccflags.U:

  This variable contains any additional C partial linker flags desired by the user. It is up to the Makefile to use this.

ln

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the ln program. After Configure runs, the value is reset to a plain ln and is not useful.

lns

  From lns.U:

  This variable holds the name of the command to make symbolic links (if they are supported). It can be used in the Makefile. It is either ln -s or ln

locincpth

  From ccflags.U:

  This variable contains a list of additional directories to be searched by the compiler. The appropriate -I directives will be added to ccflags. This is intended to simplify setting local directories from the Configure command line. It's not much, but it parallels the loclibpth stuff in libpth.U.

loclibpth

  From libpth.U:

  This variable holds the paths used to find local libraries. It is prepended to libpth, and is intended to be easily set from the command line.

longdblsize

  From d_longdbl.U:

  This variable contains the value of the `LONG_DOUBLESIZE` symbol, which indicates to the C program how many bytes there are in a long double, if this system supports long doubles.

longlongsize

  From d_longlong.U:

  This variable contains the value of the `LONGLONGSIZE` symbol, which indicates to the C program how many bytes there are in a long long, if this system supports long long.

longsize

  From intsize.U:

  This variable contains the value of the `LONGSIZE` symbol, which indicates to the C program how many bytes there are in a long.

lp

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

lpr

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

ls

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the ls program. After Configure runs, the value is reset to a plain ls and is not useful.

lseektype

  From lseektype.U:

  This variable defines lseektype to be something like off_t, long, or whatever type is used to declare lseek offset's type in the kernel (which also appears to be lseek's return type).

## m

mail

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

mailx

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

make

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the make program. After Configure runs, the value is reset to a plain make and is not useful.

make_set_make

  From make.U:

  Some versions of make set the variable `MAKE`. Others do not. This variable contains the string to be included in Makefile.SH so that `MAKE` is set if needed, and not if not needed. Possible values are: make_set_make=`#` # If your make program handles this for you, make_set_make=`MAKE=$make` # if it doesn't. I used a comment character so that we can distinguish a `set` value (from a previous config.sh or Configure -D option) from an uncomputed value.

mallocobj

  From mallocsrc.U:

  This variable contains the name of the malloc.o that this package generates, if that malloc.o is preferred over the system malloc. Otherwise the value is null. This variable is intended for generating Makefiles. See mallocsrc.

mallocsrc

  From mallocsrc.U:

  This variable contains the name of the malloc.c that comes with the package, if that malloc.c is preferred over the system malloc. Otherwise the value is null. This variable is intended for generating Makefiles.

malloctype

  From mallocsrc.U:

  This variable contains the kind of ptr returned by malloc and realloc.

man1dir

  From man1dir.U:

  This variable contains the name of the directory in which manual source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself.

man1direxp

  From man1dir.U:

  This variable is the same as the man1dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

man1ext

  From man1dir.U:

  This variable contains the extension that the manual page should have: one of n, l, or `1`. The Makefile must supply the .. See man1dir.

man3dir

  From man3dir.U:

  This variable contains the name of the directory in which manual source pages are to be put. It is the responsibility of the Makefile.SH to get the value of this into the proper command. You must be prepared to do the ~name expansion yourself.

man3direxp

  From man3dir.U:

  This variable is the same as the man3dir variable, but is filename expanded at configuration time, for convenient use in makefiles.

man3ext

  From man3dir.U:

  This variable contains the extension that the manual page should have: one of n, l, or `3`. The Makefile must supply the .. See man3dir.

medium

  From models.U:

  This variable contains a flag which will tell the C compiler and loader to produce a program running with a medium memory model. If the medium model is not supported, contains the flag to produce large model programs. It is up to the Makefile to use this.

mips_type

  From usrinc.U:

  This variable holds the environment type for the mips system. Possible values are ``BSD 4.3'' and ``System V''.

mkdir

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the mkdir program. After Configure runs, the value is reset to a plain mkdir and is not useful.

models

  From models.U:

  This variable contains the list of memory models supported by this system. Possible component values are none, split, unsplit, small, medium, large, and huge. The component values are space separated.

modetype

  From modetype.U:

  This variable defines modetype to be something like mode_t, int, unsigned short, or whatever type is used to declare file modes for system calls.

more

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the more program. After Configure runs, the value is reset to a plain more and is not useful.

mv

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

myarchname

  From archname.U:

  This variable holds the architecture name computed by Configure in a previous run. It is not intended to be perused by any user and should never be set in a hint file.

mydomain

  From myhostname.U:

  This variable contains the eventual value of the `MYDOMAIN` symbol, which is the domain of the host the program is going to run on. The domain must be appended to myhostname to form a complete host name. The dot comes with mydomain, and need not be supplied by the program.

myhostname

  From myhostname.U:

  This variable contains the eventual value of the `MYHOSTNAME` symbol, which is the name of the host the program is going to run on. The domain is not kept with hostname, but must be gotten from mydomain. The dot comes with mydomain, and need not be supplied by the program.

myuname

  From Oldconfig.U:

  The output of `uname -a` if available, otherwise the hostname. On Xenix, pseudo variables assignments in the output are stripped, thank you. The whole thing is then lower-cased.

## n

n

  From n.U:

  This variable contains the -n flag if that is what causes the echo command to suppress newline. Otherwise it is null. Correct usage is

              $echo $n "prompt for a question: $c".

netdb_hlen_type

  From netdbtype.U:

  This variable holds the type used for the 2nd argument to `gethostbyaddr().` Usually, this is int or size_t or unsigned. This is only useful if you have `gethostbyaddr(),` naturally.

netdb_host_type

  From netdbtype.U:

  This variable holds the type used for the 1st argument to `gethostbyaddr().` Usually, this is char * or void *, possibly with or without a const prefix. This is only useful if you have `gethostbyaddr(),` naturally.

netdb_name_type

  From netdbtype.U:

  This variable holds the type used for the argument to `gethostbyname().` Usually, this is char * or const char *. This is only useful if you have `gethostbyname(),` naturally.

netdb_net_type

  From netdbtype.U:

  This variable holds the type used for the 1st argument to `getnetbyaddr().` Usually, this is int or long. This is only useful if you have `getnetbyaddr(),` naturally.

nm

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the nm program. After Configure runs, the value is reset to a plain nm and is not useful.

nm_opt

  From usenm.U:

  This variable holds the options that may be necessary for nm.

nm_so_opt

  From usenm.U:

  This variable holds the options that may be necessary for nm to work on a shared library but that can not be used on an archive library. Currently, this is only used by Linux, where nm --dynamic is *required* to get symbols from an `ELF` library which has been stripped, but nm --dynamic is *fatal* on an archive library. Maybe Linux should just always set usenm=false.

nonxs_ext

  From Extensions.U:

  This variable holds a list of all non-xs extensions included in the package. All of them will be built.

nroff

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the nroff program. After Configure runs, the value is reset to a plain nroff and is not useful.

## o

o_nonblock

  From nblock_io.U:

  This variable bears the symbol value to be used during `open()` or `fcntl()` to turn on non-blocking I/O for a file descriptor. If you wish to switch between blocking and non-blocking, you may try `ioctl(``FIOSNBIO`) instead, but that is only supported by some devices.

obj_ext

  From Unix.U:

  This is an old synonym for _o.

optimize

  From ccflags.U:

  This variable contains any optimizer/debugger flag that should be used. It is up to the Makefile to use it.

orderlib

  From orderlib.U:

  This variable is true if the components of libraries must be ordered (with `lorder $* | tsort`) before placing them in an archive. Set to false if ranlib or ar can generate random libraries.

osname

  From Oldconfig.U:

  This variable contains the operating system name (e.g. sunos, solaris, hpux, etc.). It can be useful later on for setting defaults. Any spaces are replaced with underscores. It is set to a null string if we can't figure it out.

osvers

  From Oldconfig.U:

  This variable contains the operating system version (e.g. 4.1.3, 5.2, etc.). It is primarily used for helping select an appropriate hints file, but might be useful elsewhere for setting defaults. It is set to '' if we can't figure it out. We try to be flexible about how much of the version number to keep, e.g. if 4.1.1, 4.1.2, and 4.1.3 are essentially the same for this package, hints files might just be os_4.0 or os_4.1, etc., not keeping separate files for each little release.

## p

package

  From package.U:

  This variable contains the name of the package being constructed. It is primarily intended for the use of later Configure units.

pager

  From pager.U:

  This variable contains the name of the preferred pager on the system. Usual values are (the full pathnames of) more, less, pg, or cat.

passcat

  From nis.U:

  This variable contains a command that produces the text of the /etc/passwd file. This is normally ``cat /etc/passwd'', but can be ``ypcat passwd'' when `NIS` is used.

patchlevel

  From patchlevel.U:

  The patchlevel level of this package. The value of patchlevel comes from the patchlevel.h file.

path_sep

  From Unix.U:

  This is an old synonym for p_ in Head.U, the character used to separate elements in the command shell search PATH.

perl

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the perl program. After Configure runs, the value is reset to a plain perl and is not useful.

perladmin

  From perladmin.U:

  Electronic mail address of the perl5 administrator.

perlpath

  From perlpath.U:

  This variable contains the eventual value of the `PERLPATH` symbol, which contains the name of the perl interpreter to be used in shell scripts and in the ``eval exec'' idiom.

pg

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the pg program. After Configure runs, the value is reset to a plain pg and is not useful.

phostname

  From myhostname.U:

  This variable contains the eventual value of the `PHOSTNAME` symbol, which is a command that can be fed to `popen()` to get the host name. The program should probably not presume that the domain is or isn't there already.

pidtype

  From pidtype.U:

  This variable defines `PIDTYPE` to be something like pid_t, int, ushort, or whatever type is used to declare process ids in the kernel.

plibpth

  From libpth.U:

  Holds the private path used by Configure to find out the libraries. Its value is prepend to libpth. This variable takes care of special machines, like the mips. Usually, it should be empty.

pmake

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

pr

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

prefix

  From prefix.U:

  This variable holds the name of the directory below which the user will install the package. Usually, this is /usr/local, and executables go in /usr/local/bin, library stuff in /usr/local/lib, man pages in /usr/local/man, etc. It is only used to set defaults for things in bin.U, mansrc.U, privlib.U, or scriptdir.U.

prefixexp

  From prefix.U:

  This variable holds the full absolute path of the directory below which the user will install the package. Derived from prefix.

privlib

  From privlib.U:

  This variable contains the eventual value of the `PRIVLIB` symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution).

privlibexp

  From privlib.U:

  This variable is the ~name expanded version of privlib, so that you may use it directly in Makefiles or shell scripts.

prototype

  From prototype.U:

  This variable holds the eventual value of `CAN_PROTOTYPE`, which indicates the C compiler can handle funciton prototypes.

ptrsize

  From ptrsize.U:

  This variable contains the value of the `PTRSIZE` symbol, which indicates to the C program how many bytes there are in a pointer.

## r

randbits

  From randbits.U:

  This variable contains the eventual value of the `RANDBITS` symbol, which indicates to the C program how many bits of random number the `rand()` function produces.

ranlib

  From orderlib.U:

  This variable is set to the pathname of the ranlib program, if it is needed to generate random libraries. Set to `:` if ar can generate random libraries or if random libraries are not supported

rd_nodata

  From nblock_io.U:

  This variable holds the return code from `read()` when no data is present. It should be -1, but some systems return 0 when `O_NDELAY` is used, which is a shame because you cannot make the difference between no data and an EOF.. Sigh!

rm

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the rm program. After Configure runs, the value is reset to a plain rm and is not useful.

rmail

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

runnm

  From usenm.U:

  This variable contains true or false depending whether the nm extraction should be performed or not, according to the value of usenm and the flags on the Configure command line.

## s

scriptdir

  From scriptdir.U:

  This variable holds the name of the directory in which the user wants to put publicly scripts for the package in question. It is either the same directory as for binaries, or a special one that can be mounted across different architectures, like /usr/share. Programs must be prepared to deal with ~name expansion.

scriptdirexp

  From scriptdir.U:

  This variable is the same as scriptdir, but is filename expanded at configuration time, for programs not wanting to bother with it.

sed

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the sed program. After Configure runs, the value is reset to a plain sed and is not useful.

selecttype

  From selecttype.U:

  This variable holds the type used for the 2nd, 3rd, and 4th arguments to select. Usually, this is `fd_set *`, if `HAS_FD_SET` is defined, and int * otherwise. This is only useful if you have `select(),` naturally.

sendmail

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the sendmail program. After Configure runs, the value is reset to a plain sendmail and is not useful.

sh

  From sh.U:

  This variable contains the full pathname of the shell used on this system to execute Bourne shell scripts. Usually, this will be /bin/sh, though it's possible that some systems will have /bin/ksh, /bin/pdksh, /bin/ash, /bin/bash, or even something such as D:/bin/sh.exe. This unit comes before Options.U, so you can't set sh with a -D option, though you can override this (and startsh) with `-O -Dsh=<EM>/bin/whatever</EM> -Dstartsh=whatever`

shar

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

sharpbang

  From spitshell.U:

  This variable contains the string #! if this system supports that construct.

shmattype

  From d_shmat.U:

  This symbol contains the type of pointer returned by `shmat().` It can be void * or `char *`.

shortsize

  From intsize.U:

  This variable contains the value of the `SHORTSIZE` symbol which indicates to the C program how many bytes there are in a short.

shrpenv

  From libperl.U:

  If the user builds a shared libperl.so, then we need to tell the perl executable where it will be able to find the installed libperl.so. One way to do this on some systems is to set the environment variable `LD_RUN_PATH` to the directory that will be the final location of the shared libperl.so. The makefile can use this with something like

              $shrpenv $(C<CC>) -o perl F<perlmain.o> $libperl $libs

              Typical values are

              shrpenv="env C<LD_RUN_PATH>=$F<archlibexp/C<CORE>>"

              or

              shrpenv=''

              See the main perl F<Makefile.SH> for actual working usage.
      Alternatively, we might be able to use a command line option such
      as -R $F<archlibexp/C<CORE>> (Solaris, NetBSD) or -Wl,-rpath
      $F<archlibexp/C<CORE>> (Linux).

shsharp

  From spitshell.U:

  This variable tells further Configure units whether your sh can handle # comments.

sig_name

  From sig_name.U:

  This variable holds the signal names, space separated. The leading SIG in signal name is removed. A `ZERO` is prepended to the list. This is currently not used.

sig_name_init

  From sig_name.U:

  This variable holds the signal names, enclosed in double quotes and separated by commas, suitable for use in the `SIG_NAME` definition below. A `ZERO` is prepended to the list, and the list is terminated with a plain 0. The leading SIG in signal names is removed. See sig_num.

sig_num

  From sig_name.U:

  This variable holds the signal numbers, comma separated. A 0 is prepended to the list (corresponding to the fake `SIGZERO`), and the list is terminated with a 0. Those numbers correspond to the value of the signal listed in the same place within the sig_name list.

signal_t

  From d_voidsig.U:

  This variable holds the type of the signal handler (void or int).

sitearch

  From sitearch.U:

  This variable contains the eventual value of the `SITEARCH` symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution).

sitearchexp

  From sitearch.U:

  This variable is the ~name expanded version of sitearch, so that you may use it directly in Makefiles or shell scripts.

sitelib

  From sitelib.U:

  This variable contains the eventual value of the `SITELIB` symbol, which is the name of the private library for this package. It may have a ~ on the front. It is up to the makefile to eventually create this directory while performing installation (with ~ substitution).

sitelibexp

  From sitelib.U:

  This variable is the ~name expanded version of sitelib, so that you may use it directly in Makefiles or shell scripts.

sizetype

  From sizetype.U:

  This variable defines sizetype to be something like size_t, unsigned long, or whatever type is used to declare length parameters for string functions.

sleep

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

smail

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

small

  From models.U:

  This variable contains a flag which will tell the C compiler and loader to produce a program running with a small memory model. It is up to the Makefile to use this.

so

  From so.U:

  This variable holds the extension used to identify shared libraries (also known as shared objects) on the system. Usually set to so.

sockethdr

  From d_socket.U:

  This variable has any cpp -I flags needed for socket support.

socketlib

  From d_socket.U:

  This variable has the names of any libraries needed for socket support.

sort

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the sort program. After Configure runs, the value is reset to a plain sort and is not useful.

spackage

  From package.U:

  This variable contains the name of the package being constructed, with the first letter uppercased, i.e. suitable for starting sentences.

spitshell

  From spitshell.U:

  This variable contains the command necessary to spit out a runnable shell on this system. It is either cat or a grep `-v` for # comments.

split

  From models.U:

  This variable contains a flag which will tell the C compiler and loader to produce a program that will run in separate I and D space, for those machines that support separation of instruction and data space. It is up to the Makefile to use this.

src

  From src.U:

  This variable holds the path to the package source. It is up to the Makefile to use this variable and set `VPATH` accordingly to find the sources remotely.

ssizetype

  From ssizetype.U:

  This variable defines ssizetype to be something like ssize_t, long or int. It is used by functions that return a count of bytes or an error condition. It must be a signed type. We will pick a type such that `sizeof(SSize_t)` == `sizeof(Size_t).`

startperl

  From startperl.U:

  This variable contains the string to put on the front of a perl script to make sure (hopefully) that it runs with perl and not some shell. Of course, that leading line must be followed by the classical perl idiom:

              eval 'exec perl -S $0 ${1+C<$@>}'

              if $running_under_some_shell;

              to guarantee perl startup should the shell execute the script. Note
      that this magic incatation is not understood by csh.

startsh

  From startsh.U:

  This variable contains the string to put on the front of a shell script to make sure (hopefully) that it runs with sh and not some other shell.

static_ext

  From Extensions.U:

  This variable holds a list of XS extension files we want to link statically into the package. It is used by Makefile.

stdchar

  From stdchar.U:

  This variable conditionally defines `STDCHAR` to be the type of char used in stdio.h. It has the values ``unsigned char'' or `char`.

stdio_base

  From d_stdstdio.U:

  This variable defines how, given a FILE pointer, fp, to access the _base field (or equivalent) of stdio.h's FILE structure. This will be used to define the macro `FILE_base(fp).`

stdio_bufsiz

  From d_stdstdio.U:

  This variable defines how, given a FILE pointer, fp, to determine the number of bytes store in the I/O buffer pointer to by the _base field (or equivalent) of stdio.h's FILE structure. This will be used to define the macro `FILE_bufsiz(fp).`

stdio_cnt

  From d_stdstdio.U:

  This variable defines how, given a FILE pointer, fp, to access the _cnt field (or equivalent) of stdio.h's FILE structure. This will be used to define the macro `FILE_cnt(fp).`

stdio_filbuf

  From d_stdstdio.U:

  This variable defines how, given a FILE pointer, fp, to tell stdio to refill it's internal buffers (?). This will be used to define the macro `FILE_filbuf(fp).`

stdio_ptr

  From d_stdstdio.U:

  This variable defines how, given a FILE pointer, fp, to access the _ptr field (or equivalent) of stdio.h's FILE structure. This will be used to define the macro `FILE_ptr(fp).`

strings

  From i_string.U:

  This variable holds the full path of the string header that will be used. Typically /usr/include/string.h or /usr/include/strings.h.

submit

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

subversion

  From patchlevel.U:

  The subversion level of this package. The value of subversion comes from the patchlevel.h file. This is unique to perl.

sysman

  From sysman.U:

  This variable holds the place where the manual is located on this system. It is not the place where the user wants to put his manual pages. Rather it is the place where Configure may look to find manual for unix commands (section 1 of the manual usually). See mansrc.

## t

tail

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

tar

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

tbl

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

tee

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the tee program. After Configure runs, the value is reset to a plain tee and is not useful.

test

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the test program. After Configure runs, the value is reset to a plain test and is not useful.

timeincl

  From i_time.U:

  This variable holds the full path of the included time `header(s).`

timetype

  From d_time.U:

  This variable holds the type returned by `time().` It can be long, or time_t on `BSD` sites (in which case <sys/types.h> should be included). Anyway, the type Time_t should be used.

touch

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the touch program. After Configure runs, the value is reset to a plain touch and is not useful.

tr

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the tr program. After Configure runs, the value is reset to a plain tr and is not useful.

trnl

  From trnl.U:

  This variable contains the value to be passed to the `tr(1)` command to transliterate a newline. Typical values are `\012` and \n. This is needed for EBCDIC systems where newline is not necessarily `\012`.

troff

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

## u

uidtype

  From uidtype.U:

  This variable defines Uid_t to be something like uid_t, int, ushort, or whatever type is used to declare user ids in the kernel.

uname

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the uname program. After Configure runs, the value is reset to a plain uname and is not useful.

uniq

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the uniq program. After Configure runs, the value is reset to a plain uniq and is not useful.

usedl

  From dlsrc.U:

  This variable indicates if the the system supports dynamic loading of some sort. See also dlsrc and dlobj.

usemymalloc

  From mallocsrc.U:

  This variable contains y if the malloc that comes with this package is desired over the system's version of malloc. People often include special versions of malloc for effiency, but such versions are often less portable. See also mallocsrc and mallocobj. If this is y, then -lmalloc is removed from $libs.

usenm

  From usenm.U:

  This variable contains true or false depending whether the nm extraction is wanted or not.

useopcode

  From Extensions.U:

  This variable holds either true or false to indicate whether the Opcode extension should be used. The sole use for this currently is to allow an easy mechanism for users to skip the Opcode extension from the Configure command line.

useperlio

  From useperlio.U:

  This variable conditionally defines the `USE_PERLIO` symbol, and indicates that the PerlIO abstraction should be used throughout.

useposix

  From Extensions.U:

  This variable holds either true or false to indicate whether the POSIX extension should be used. The sole use for this currently is to allow an easy mechanism for hints files to indicate that POSIX will not compile on a particular system.

usesfio

  From d_sfio.U:

  This variable is set to true when the user agrees to use sfio. It is set to false when sfio is not available or when the user explicitely requests not to use sfio. It is here primarily so that command-line settings can override the auto-detection of d_sfio without running into a ``WHOA THERE''.

useshrplib

  From libperl.U:

  This variable is set to `yes` if the user wishes to build a shared libperl, and no otherwise.

usethreads

  From usethreads.U:

  This variable conditionally defines the `USE_THREADS` symbol, and indicates that Perl should be built to use threads.

usevfork

  From d_vfork.U:

  This variable is set to true when the user accepts to use vfork. It is set to false when no vfork is available or when the user explicitely requests not to use vfork.

usrinc

  From usrinc.U:

  This variable holds the path of the include files, which is usually /usr/include. It is mainly used by other Configure units.

uuname

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

## v

version

  From patchlevel.U:

  The full version number of this package. This combines baserev, patchlevel, and subversion to get the full version number, including any possible subversions. Care is taken to use the C locale in order to get something like 5.004 instead of 5,004. This is unique to perl.

vi

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

voidflags

  From voidflags.U:

  This variable contains the eventual value of the `VOIDFLAGS` symbol, which indicates how much support of the void type is given by this compiler. See `VOIDFLAGS` for more info.

## z

zcat

  From Loc.U:

  This variable is defined but not used by Configure. The value is a plain '' and is not useful.

zip

  From Loc.U:

  This variable is be used internally by Configure to determine the full pathname (if any) of the zip program. After Configure runs, the value is reset to a plain zip and is not useful.

# NOTE

This module contains a good example of how to use tie to implement a cache and an example of how to make a tied variable readonly to those outside of it.