\section{Ebuild-specific commands}
\label{sec:pkg-mgr-commands}

The following commands will always be available in the ebuild environment, provided by the package
manager. Except where otherwise noted, they may be internal (shell functions or aliases) or external
commands available in \t{PATH}; where this is not specified, ebuilds may not rely upon either
behaviour. Unless otherwise specified, it is an error if an ebuild calls any of these commands in
global scope.

Unless otherwise noted, any output of these commands ends with a newline.

\subsection{Failure behaviour and related commands}
\label{sec:failure-behaviour}

\featurelabel{die-on-failure} Where a command is listed as having EAPI dependent failure behaviour,
a failure shall either result in a non-zero exit status or abort the build process, as determined by
table~\ref{tab:commands-die-table}.

The following commands affect this behaviour:
\nobreakpar
\begin{description}
\item[nonfatal] \featurelabel{nonfatal} Takes one or more arguments and executes them as a command,
    preserving the exit status. If this results in a command being called that would normally abort
    the build process due to a failure, instead a non-zero exit status shall be returned. Only in
    EAPIs listed in table~\ref{tab:commands-die-table} as supporting \t{nonfatal}.

    In EAPIs listed in table~\ref{tab:commands-die-table} as having \t{nonfatal} defined both
    as a shell function and as an external command, the package manager must provide both
    implementations to account for calling directly in ebuild scope or through \t{xargs}.

    Explicit \t{die} or \t{assert} commands only respect \t{nonfatal} when called with the \t{-n}
    option and in EAPIs supporting this option, see table~\ref{tab:die-properties}.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPI command failure behaviour}
    \label{tab:commands-die-table}
    \begin{tabular}{llll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{P{8em}}{\textbf{Command failure behaviour}} &
      \multicolumn{1}{P{5em}}{\textbf{Supports \t{nonfatal}?}} &
      \multicolumn{1}{P{12em}}{\textbf{\t{nonfatal} is both a function and an external command?}} \\
      \midrule
      0, 1, 2, 3        & Non-zero exit & No  & n/a \\
      4, 5, 6           & Aborts        & Yes & No  \\
      7, 8, 9           & Aborts        & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Banned commands}
\label{sec:banned-commands}

\featurelabel{banned-commands} Some commands are banned in some EAPIs. If a banned command is
called, the package manager must abort the build process indicating an error.

\ChangeWhenAddingAnEAPI{9}  % two places
\begin{centertable}{Banned commands}
    \label{tab:banned-commands-table}
    \begin{tabular}{lllllll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{6}{c}{\textbf{Command banned?}} \\
      \multicolumn{1}{c}{} &
      \multicolumn{1}{c}{\textbf{\t{dohard}}} &
      \multicolumn{1}{c}{\textbf{\t{dosed}}} &
      \multicolumn{1}{c}{\textbf{\t{einstall}}} &
      \multicolumn{1}{c}{\textbf{\t{dohtml}}} &
      \multicolumn{1}{c}{\textbf{\t{dolib}}} &
      \multicolumn{1}{c}{\textbf{\t{libopts}}} \\
      \midrule
      0, 1, 2, 3        & No  & No  & No  & No  & No  & No  \\
      4, 5              & Yes & Yes & No  & No  & No  & No  \\
      6                 & Yes & Yes & Yes & No  & No  & No  \\
      7, 8, 9           & Yes & Yes & Yes & Yes & Yes & Yes \\
      \midrule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{6}{c}{\textbf{Command banned?}} \\
      \multicolumn{1}{c}{} &
      \multicolumn{1}{c}{\textbf{\t{useq}}} &
      \multicolumn{1}{c}{\textbf{\t{hasv}}} &
      \multicolumn{1}{c}{\textbf{\t{hasq}}} &
      \multicolumn{1}{c}{\textbf{\t{assert}}} &
      \multicolumn{1}{c}{\textbf{\t{domo}}} & \\
      \midrule
      0, 1, 2, 3, 4, 5, 6, 7  & No  & No  & No  & No  & No  & \\
      8                       & Yes & Yes & Yes & No  & No  & \\
      9                       & Yes & Yes & Yes & Yes & Yes & \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Sandbox commands}
These commands affect the behaviour of the sandbox. Each command takes a single path as argument.
Ebuilds must not run any of these commands once the current phase function has returned.
\begin{description}
\item[addread] Add a path to the permitted read list.
\item[addwrite] Add a path to the permitted write list.
\item[addpredict] Add a path to the predict list. Any write to a location in this list will be
    denied, but will not trigger access violation messages or abort the build process.
\item[adddeny] Add a path to the deny list.
\end{description}

\subsection{Package manager query commands}
These commands are used to extract information about the system. Ebuilds must not run any of
these commands in parallel with any other package manager command. Ebuilds must not run any of
these commands once the current phase function has returned.

\featurelabel{pm-query-options} In EAPIs listed in table~\ref{tab:pm-query-options} as supporting
option \t{-{}-host-root}, this flag as the first argument will cause the query to apply to the
host root. Otherwise, it applies to \t{ROOT}.

In EAPIs listed in table~\ref{tab:pm-query-options} as supporting options \t{-b}, \t{-d} and \t{-r},
these mutually exclusive flags as the first argument will cause the query to apply to locations
targetted by \t{BDEPEND}, \t{DEPEND} and \t{RDEPEND}, respectively. When none of these options
are given, \t{-r} is assumed.

\begin{description}
\item[has_version] Takes exactly one package dependency specification as an argument. Returns
    true if a package matching the specification is installed, and false otherwise.
\item[best_version] Takes exactly one package dependency specification as an argument. If a matching
    package is installed, prints \t{category/package-version} of the highest matching version;
    otherwise, prints an empty string. The exit code is unspecified.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Package manager query command options supported by EAPIs}
    \label{tab:pm-query-options}
    \begin{tabular}{lllll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{-{}-host-root}?}} &
      \multicolumn{1}{c}{\textbf{\t{-b}?}} &
      \multicolumn{1}{c}{\textbf{\t{-d}?}} &
      \multicolumn{1}{c}{\textbf{\t{-r}?}} \\
      \midrule
      0, 1, 2, 3, 4     & No  & No  & No  & No  \\
      5, 6              & Yes & No  & No  & No  \\
      7, 8, 9           & No  & Yes & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Output commands}
These commands display messages to the user. Unless otherwise stated, the entire argument list is
used as a message, with backslash-escaped characters interpreted as for the \t{echo -e} command of
bash, notably \t{\textbackslash t} for a horizontal tab, \t{\textbackslash n} for a new line, and
\t{\textbackslash\textbackslash} for a literal backslash. These commands must be implemented
internally as shell functions and may be called in global scope. Ebuilds must not run any of these
commands once the current phase function has returned.

\featurelabel{output-no-stdout} Unless otherwise noted, output may be sent to stderr or some other
appropriate facility. In EAPIs listed in table~\ref{tab:output-commands} as not allowing stdout
output, using stdout as an output facility is forbidden.

\begin{description}
\item[einfo] Displays an informational message.
\item[einfon] Displays an informational message without a trailing newline.
\item[elog] Displays an informational message of slightly higher importance. The package
    manager may choose to log \t{elog} messages by default where \t{einfo} messages are not, for
    example.
\item[ewarn] Displays a warning message. Must not go to stdout.
\item[eqawarn] \featurelabel{eqawarn} Display a QA warning message intended for ebuild developers.
    The package manager may provide appropriate mechanisms to skip those messages for normal users.
    Must not go to stdout. Only available in EAPIs listed in table~\ref{tab:output-commands} as
    supporting \t{eqawarn}.
\item[eerror] Displays an error message. Must not go to stdout.
\item[ebegin] Displays an informational message. Should be used when beginning a possibly
    lengthy process, and followed by a call to \t{eend}.
\item[eend] Indicates that the process begun with an \t{ebegin} message has completed. Takes one
    fixed argument, which is a numeric return code, and an optional message in all subsequent
    arguments. If the first argument is 0, prints a success indicator; otherwise, prints the
    message followed by a failure indicator. Returns its first argument as exit status.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Output commands for EAPIs}
    \label{tab:output-commands}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Commands can output to stdout?}} &
      \multicolumn{1}{c}{\textbf{Supports \t{eqawarn}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6 & Yes & No  \\
      7, 8, 9             & No  & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Error commands}
These commands are used when an error is detected that will prevent the build process from
completing. Ebuilds must not run any of these commands once the current phase function has returned.
\begin{description}
\item[die] \featurelabel{nonfatal-die} If called under the \t{nonfatal} command (as per
    section~\ref{sec:failure-behaviour}) and with \t{-n} as its first parameter, displays a failure
    message provided in its following argument and then returns a non-zero exit status. Only in
    EAPIs listed in table~\ref{tab:die-properties} as supporting option~\t{-n}. Otherwise, displays
    a failure message provided in its first and only argument, and then aborts the build process.

    \featurelabel{subshell-die} In EAPIs listed in table~\ref{tab:die-properties} as not providing
    subshell support, \t{die} is \emph{not} guaranteed to work correctly if called from a subshell
    environment.
\item[assert] Checks the shell's pipe status array, and if any element is non-zero (indicating
    failure), calls \t{die}, passing any parameters to it.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.
\item[pipestatus] \featurelabel{pipestatus} Checks the shell's pipe status array, i.\,e.\ the exit
    status of the command(s) in the most recently executed foreground pipeline. Returns shell true
    (0) if all elements are zero, or the last non-zero element otherwise. If called with \t{-v}
    as the first argument, also outputs the pipe status array as a space-separated list.
    Only available in EAPIs listed in table~\ref{tab:pipestatus} as supporting \t{pipestatus}.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Properties of \t{die} command in EAPIs}
    \label{tab:die-properties}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Supports \t{die -n}?}} &
      \multicolumn{1}{c}{\textbf{\t{die} works in subshell?}} \\
      \midrule
      0, 1, 2, 3, 4, 5  & No  & No  \\
      6                 & Yes & No  \\
      7, 8, 9           & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting \t{pipestatus}}
    \label{tab:pipestatus}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Supports \t{pipestatus}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6, 7, 8 & No  \\
      9                         & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Patch commands}
These commands are used during the \t{src_prepare} phase to apply patches to the package's sources.
Ebuilds must not run any of these commands once the current phase function has returned.

\begin{description}
\item[eapply] \featurelabel{eapply} Takes zero or more GNU patch options, followed by one or more
    file or directory paths. Processes options and applies all patches found in specified locations
    according to algorithm~\ref{alg:eapply}. If applying the patches fails, it aborts the build
    using \t{die}, unless run using \t{nonfatal}, in which case it returns non-zero exit status.
    Only available in EAPIs listed in table~\ref{tab:patch-commands} as supporting \t{eapply}.

\begin{algorithm}
\caption{\t{eapply} logic} \label{alg:eapply}
\begin{algorithmic}[1]
\IF{any parameter is equal to \t{"-{}-"}}
    \STATE collect all parameters before the first \t{"-{}-"} in the \t{options} array
    \STATE collect all parameters after the first \t{"-{}-"} in the \t{files} array
\ELSIF{any parameter that begins with a hyphen follows one that does not}
    \STATE abort the build process with an error
\ELSE
    \STATE collect all parameters beginning with a hyphen in the \t{options} array
    \STATE collect all remaining parameters in the \t{files} array
\ENDIF
\IF{the \t{files} array is empty}
    \STATE abort the build process with an error
\ENDIF
\FORALL{\t{x} in the \t{files} array}
    \IF{\t{\$x} is a directory}
        \IF{\NOT any files match \t{\$x/*.diff} or \t{\$x/*.patch}}
            \STATE abort the build process with an error
        \ENDIF
        \FORALL{files \t{f} matching \t{\$x/*.diff} or \t{\$x/*.patch}, sorted in POSIX locale}
            \STATE call \t{patch -p1 -f -g0 -{}-no-backup-if-mismatch "\$\{options[@]\}" < "\$f"}
            \IF{child process returned with non-zero exit status}
                \RETURN immediately with that status
            \ENDIF
        \ENDFOR
    \ELSE
        \STATE call \t{patch -p1 -f -g0 -{}-no-backup-if-mismatch "\$\{options[@]\}" < "\$x"}
        \IF{child process returned with non-zero exit status}
            \RETURN immediately with that status
        \ENDIF
    \ENDIF
\ENDFOR
\RETURN shell true (0)
\end{algorithmic}
\end{algorithm}

\item[eapply_user] \featurelabel{eapply-user} Takes no arguments. Package managers supporting it
    apply user-provided patches to the source tree in the current working directory. Exact behaviour
    is implementation defined and beyond the scope of this specification. Package managers not
    supporting it must implement the command as a no-op. Returns shell true (0) if patches applied
    successfully, or if no patches were provided. Otherwise, aborts the build process, unless run
    using \t{nonfatal}, in which case it returns non-zero exit status. Only available in EAPIs
    listed in table~\ref{tab:patch-commands} as supporting \t{eapply_user}. In EAPIs where it is
    supported, \t{eapply_user} must be called once in the \t{src_prepare} phase. For any
    subsequent calls, the command will do nothing and return~0.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Patch commands for EAPIs}
    \label{tab:patch-commands}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{eapply}?}} &
      \multicolumn{1}{c}{\textbf{\t{eapply_user}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5  & No  & No  \\
      6, 7, 8, 9        & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Build commands}
\label{sec:build-commands}
These commands are used during the \t{src_configure}, \t{src_compile}, \t{src_test},
and \t{src_install} phases to run the package's build commands. Ebuilds must not run any of these
commands once the current phase function has returned.

\begin{description}
\item[econf] Calls the program's \t{./configure} script. This is designed to work with GNU
    Autoconf-generated scripts. Any additional parameters passed to \t{econf} are passed directly
    to \t{./configure}, after the default options below. \t{econf} will look in the current working
    directory for a configure script unless the \t{ECONF_SOURCE} environment variable is set,
    in which case it is taken to be the directory containing it.

    \featurelabel{econf-options} \t{econf} must pass the following options to the configure script:
    \begin{itemize}
    \item \t{-{}-prefix} must default to \t{\$\{EPREFIX\}/usr} unless overridden by \t{econf}'s
        caller.
    \item \t{-{}-mandir} must be \t{\$\{EPREFIX\}/usr/share/man}
    \item \t{-{}-infodir} must be \t{\$\{EPREFIX\}/usr/share/info}
    \item \t{-{}-datadir} must be \t{\$\{EPREFIX\}/usr/share}
    \item \t{-{}-datarootdir} must be \t{\$\{EPREFIX\}/usr/share}, if the EAPI is listed in
        table~\ref{tab:econf-options-table} as using it. This option will only be passed if the
        string \t{-{}-datarootdir} occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-sysconfdir} must be \t{\$\{EPREFIX\}/etc}
    \item \t{-{}-localstatedir} must be \t{\$\{EPREFIX\}/var/lib}
    \item \t{-{}-docdir} must be \t{\$\{EPREFIX\}/usr/share/doc/\$\{PF\}}, if the EAPI is listed in
        table~\ref{tab:econf-options-table} as using it. This option will only be passed if the
        string \t{-{}-docdir} occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-htmldir} must be \t{\$\{EPREFIX\}/usr/share/doc/\$\{PF\}/html}, if the EAPI is
        listed in table~\ref{tab:econf-options-table} as using it. This option will only be passed
        if the string \t{-{}-htmldir} occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-with-sysroot} must be \t{\$\{ESYSROOT:-/\}}, if the EAPI is listed in
        table~\ref{tab:econf-options-table} as using it. This option will only be passed if the
        string \t{-{}-with-sysroot} occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-build} must be the value of the \t{CBUILD} environment variable. This option will
        only be passed if \t{CBUILD} is non-empty.
    \item \t{-{}-host} must be the value of the \t{CHOST} environment variable.
    \item \t{-{}-target} must be the value of the \t{CTARGET} environment variable. This option will
        only be passed if \t{CTARGET} is non-empty.
    \item \t{-{}-libdir} must be set according to algorithm~\ref{alg:econf-libdir}.
    \item \t{-{}-disable-dependency-tracking}, if the EAPI is listed in
        table~\ref{tab:econf-options-table} as using it. This option will only be passed if the
        string \t{-{}-disable-dependency-tracking} occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-disable-silent-rules}, if the EAPI is listed in table~\ref{tab:econf-options-table}
        as using it. This option will only be passed if the string \t{-{}-disable-silent-rules}
        occurs in the output of \t{configure -{}-help}.
    \item \t{-{}-disable-static}, if the EAPI is listed in table~\ref{tab:econf-options-table}
        as using it. This option will only be passed if both strings \t{-{}-enable-static} and
        \t{-{}-enable-shared} occur in the output of \t{configure -{}-help}.
    \end{itemize}

    For the option names beginning with \t{with-}, \t{disable-} or \t{enable-}, a string in
    \t{configure -{}-help} output matches only if it is not immediately followed by any of the
    characters \t{[A-Za-z0-9+_.-]}.

    \ChangeWhenAddingAnEAPI{9}  % two places
    \begin{centertable}{Extra \t{econf} arguments for EAPIs}
        \label{tab:econf-options-table}
        \begin{tabular}{lllll}
          \toprule
          \multicolumn{1}{c}{\textbf{EAPI}} &
          \multicolumn{1}{c}{\textbf{-{}-datarootdir}} &
          \multicolumn{1}{c}{\textbf{-{}-docdir}} &
          \multicolumn{1}{c}{\textbf{-{}-htmldir}} &
          \multicolumn{1}{c}{\textbf{-{}-with-sysroot}} \\
          \midrule
          0, 1, 2, 3, 4, 5  & No  & No  & No  & No  \\
          6                 & No  & Yes & Yes & No  \\
          7                 & No  & Yes & Yes & Yes \\
          8, 9              & Yes & Yes & Yes & Yes \\
          \midrule
          \multicolumn{1}{c}{\textbf{EAPI}} &
          \multicolumn{1}{P{5.5em}}{\textbf{-{}-disable-dependency-tracking}} &
          \multicolumn{1}{P{5em}}{\textbf{-{}-disable-silent-rules}} &
          \multicolumn{1}{c}{\textbf{-{}-disable-static}} & \\
          \midrule
          0, 1, 2, 3        & No  & No  & No  & \\
          4                 & Yes & No  & No  & \\
          5, 6, 7           & Yes & Yes & No  & \\
          8, 9              & Yes & Yes & Yes & \\
          \bottomrule
        \end{tabular}
    \end{centertable}

    Note that the \t{\$\{EPREFIX\}} component represents the same offset-prefix as described in
    table~\ref{tab:defined-vars}. It facilitates offset-prefix installations which is supported by
    EAPIs listed in table~\ref{tab:offset-env-vars-table}. When no offset-prefix installation is in
    effect, \t{EPREFIX} becomes the empty string, making the behaviour of \t{econf} equal for both
    offset-prefix supporting and agnostic EAPIs.

    \t{econf} must be implemented internally---that is, as a bash function and not an external
    script. Should any portion of it fail, it must abort the build using \t{die}, unless run using
    \t{nonfatal}, in which case it must return non-zero exit status.

\begin{algorithm}
\caption{\t{econf -{}-libdir} logic} \label{alg:econf-libdir}
\begin{algorithmic}[1]
\STATE let prefix=\$\{EPREFIX\}/usr
\IF{the caller specified -{}-exec-prefix=\$ep}
    \STATE let prefix=\$ep
\ELSIF{the caller specified -{}-prefix=\$p}
    \STATE let prefix=\$p
\ENDIF
\STATE let libdir=
\IF{the ABI environment variable is set}
    \STATE let libvar=LIBDIR_\$ABI
    \IF{the environment variable named by libvar is set}
        \STATE let libdir=the value of the variable named by libvar
    \ENDIF
\ENDIF
\IF{libdir is non-empty}
    \STATE pass -{}-libdir=\$prefix/\$libdir to configure
\ENDIF
\end{algorithmic}
\end{algorithm}

\item[emake] Calls the \t{\$\{MAKE\}} program, or GNU make if the \t{MAKE} variable is unset.
    Any arguments given are passed directly to the make command, as are the user's chosen
    \t{MAKEOPTS}\@. Arguments given to \t{emake} override user configuration. See also
    section~\ref{sec:guaranteed-system-commands}. \t{emake} must be an external program and cannot
    be a function or alias---it must be callable from e.\,g.\ \t{xargs}. Failure behaviour is EAPI
    dependent as per section~\ref{sec:failure-behaviour}.

\item[einstall] A shortcut for the command given in listing~\ref{lst:einstall}. Any arguments given
    to \t{einstall} are passed verbatim to \t{emake}, as shown. Failure behaviour is EAPI dependent
    as per section~\ref{sec:failure-behaviour}.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.

    The variable \t{ED} is defined as in table~\ref{tab:defined-vars} and depends on the use of an
    offset-prefix. When such offset-prefix is absent, \t{ED} is equivalent to \t{D}\@. \t{ED} is
    always available in EAPIs that support offset-prefix installations as listed in
    table~\ref{tab:offset-env-vars-table}, hence EAPIs lacking offset-prefix support should use
    \t{D} instead of \t{ED} in the command given in listing~\ref{lst:einstall}.
    Variable \t{libdir} is an auxiliary local variable whose value is determined by
    algorithm~\ref{alg:get-libdir}.

\begin{listing}[H]
\caption{\t{einstall} command} \label{lst:einstall}
\begin{verbatim}
emake \
    prefix="${ED}"/usr \
    datadir="${ED}"/usr/share \
    mandir="${ED}"/usr/share/man \
    infodir="${ED}"/usr/share/info \
    libdir="${ED}"/usr/${libdir} \
    localstatedir="${ED}"/var/lib \
    sysconfdir="${ED}"/etc \
    -j1 \
    "$@" \
    install
\end{verbatim}
\end{listing}

\end{description}

\subsection{Installation commands}
These commands are used to install files into the staging area, in cases where the package's \t{make
install} target cannot be used or does not install all needed files. Except where otherwise stated,
all filenames created or modified are relative to the staging directory including the offset-prefix
\t{ED} in offset-prefix aware EAPIs, or just the staging directory \t{D} in offset-prefix agnostic
EAPIs. Existing destination files are overwritten. These commands must all be external programs and
not bash functions or aliases---that is, they must be callable from \t{xargs}. Calling any of these
commands without a filename parameter is an error. Ebuilds must not run any of these commands once
the current phase function has returned.

\begin{description}
\item[dobin] Installs the given files into \t{DESTTREE/bin}, where \t{DESTTREE} defaults to
    \t{/usr}. Gives the files mode \t{0755} and transfers file ownership to the superuser or its
    equivalent on the system or installation at hand. In a non-offset-prefix installation this
    ownership is \t{0:0}, while in an offset-prefix aware installation this may be e.\,g.\
    \t{joe:users}. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[doconfd] Installs the given config files into \t{/etc/conf.d/}, by default with file mode
    \t{0644}. For EAPIs listed in table~\ref{tab:insopts-commands} as respecting \t{insopts}
    in \t{doconfd}, the \t{install} options set by the most recent \t{insopts} call override
    the default. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[dodir] Creates the given directories, by default with file mode \t{0755}, or with the
    \t{install} options set by the most recent \t{diropts} call. Failure behaviour is EAPI
    dependent as per section~\ref{sec:failure-behaviour}.

\item[dodoc] \featurelabel{dodoc} Installs the given files into a subdirectory under
    \t{/usr/share/doc/\$\{PF\}/} with file mode \t{0644}. The subdirectory is set by the most
    recent call to \t{docinto}. If \t{docinto} has not yet been called, instead installs to the
    directory \t{/usr/share/doc/\$\{PF\}/}. For EAPIs listed in table~\ref{tab:dodoc-table}
    as supporting \t{-r}, if the first argument is \t{-r}, any subsequent arguments that are
    directories are installed recursively to the appropriate location; in any other case, it is
    an error for a directory to be specified. Any directories that don't already exist are created
    using \t{install -d} with no additional options. Failure behaviour is EAPI dependent as per
    section~\ref{sec:failure-behaviour}.

\item[doenvd] Installs the given environment files into \t{/etc/env.d/}, by default with file mode
    \t{0644}. For EAPIs listed in table~\ref{tab:insopts-commands} as respecting \t{insopts}
    in \t{doenvd}, the \t{install} options set by the most recent \t{insopts} call override
    the default. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[doexe] Installs the given files into the directory specified by the most recent \t{exeinto}
    call. If \t{exeinto} has not yet been called, behaviour is undefined. Files are installed by
    default with file mode \t{0755}, or with the \t{install} options set by the most recent
    \t{exeopts} call.
    Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[dohard] Takes two parameters. Creates a hardlink from the second to the first. Both paths are
    relative to the staging directory including the offset-prefix \t{ED} in offset-prefix aware
    EAPIs, or just the staging directory \t{D} in offset-prefix agnostic EAPIs. In EAPIs listed
    in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.

\item[doheader] \featurelabel{doheader} Installs the given header files into \t{/usr/include/},
    by default with file mode \t{0644}. For EAPIs listed in table~\ref{tab:insopts-commands}
    as respecting \t{insopts} in \t{doheader}, the \t{install} options set by the most recent
    \t{insopts} call override the default. If the first argument is \t{-r}, then operates
    recursively, descending into any directories given.
    Only available in EAPIs listed in table~\ref{tab:doheader-table} as supporting \t{doheader}.
    Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[dohtml] Installs the given HTML files into a subdirectory under \t{/usr/share/doc/\$\{PF\}/}.
    The subdirectory is \t{html} by default, but this can be overridden with the \t{docinto}
    function. Files to be installed automatically are determined by extension and the default
    extensions are \t{css}, \t{gif}, \t{htm}, \t{html}, \t{jpeg}, \t{jpg}, \t{js} and \t{png}.
    These default extensions can be extended or reduced (see below). The options that can be passed
    to \t{dohtml} are as follows:
    \begin{compactdesc}
    \item[\t{-r}] enables recursion into directories.
    \item[\t{-V}] enables verbosity.
    \item[\t{-A}] adds file type extensions to the default list.
    \item[\t{-a}] sets file type extensions to only those specified.
    \item[\t{-f}] list of files that are able to be installed.
    \item[\t{-x}] list of directories that files will not be installed from (only used in
        conjunction with \t{-r}).
    \item[\t{-p}] sets a document prefix for installed files, not to be confused with the global
        offset-prefix.
    \end{compactdesc}

    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.
    Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

    It is undefined whether a failure shall occur if \t{-r} is not specified and a directory is
    encountered. Ebuilds must not rely upon any particular behaviour.

\item[doinfo] Installs the given GNU Info files into the \t{/usr/share/info} area with file mode
    \t{0644}. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[doinitd] Installs the given initscript files into \t{/etc/init.d}, by default with file mode
    \t{0755}. For EAPIs listed in table~\ref{tab:insopts-commands} as respecting \t{insopts}
    in \t{doinitd}, the \t{install} options set by the most recent \t{exeopts} call override
    the default. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[doins] \featurelabel{doins} Takes one or more files as arguments and installs them into
    \t{INSDESTTREE}, by default with file mode \t{0644}, or with the \t{install} options set by
    the most recent \t{insopts} call. If the first argument is \t{-r}, then operates recursively,
    descending into any directories given. Any directories are created as if \t{dodir} was called.
    For EAPIs listed in table~\ref{tab:doins-table}, \t{doins} must install symlinks as symlinks;
    for other EAPIs, behaviour is undefined if any symlink is encountered. Failure behaviour is
    EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[dolib.a] For each argument, installs it into the appropriate library subdirectory under
    \t{DESTTREE}, as determined by algorithm~\ref{alg:get-libdir}. Files are installed with file
    mode \t{0644}. Any symlinks are installed into the same directory as relative links to their
    original target. Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[dolib.so] As for \t{dolib.a} except each file is installed with mode \t{0755}.

\item[dolib] As for \t{dolib.a} except that the default install mode can be overriden with
    the \t{install} options set by the most recent \t{libopts} call. In EAPIs listed
    in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.

\item[doman] Installs the given man pages into the appropriate subdirectory of \t{/usr/share/man}
    depending upon its apparent section suffix (e.\,g.\ \t{foo.1} goes to
    \t{/usr/share/man/man1/foo.1}) with file mode \t{0644}.

    \featurelabel{doman-langs} In EAPIs listed in table~\ref{tab:doman-table} as supporting
    language detection by filename, a man page with name of the form \t{foo.}\i{lang}\t{.1} shall
    go to \t{/usr/share/man/}\i{lang}\t{/man1/foo.1}, where \i{lang} refers to a pair of lower-case
    ASCII letters optionally followed by an underscore and a pair of upper-case ASCII letters.
    Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

    With option \t{-i18n=}\i{lang}, a man page shall be installed into an appropriate subdirectory
    of \t{/usr/share/man/}\i{lang} (e.\,g.\ \t{/usr/share/man/}\i{lang}\t{/man1/foo.pl.1} would be
    the destination for \t{foo.pl.1}). The \i{lang} subdirectory level is skipped if \i{lang} is
    the empty string. In EAPIs specified by table~\ref{tab:doman-table}, the \t{-i18n} option takes
    precedence over the language code in the filename.

\item[domo] \featurelabel{domo-path} Installs the given \t{.mo} files with file mode \t{0644} into
    the appropriate subdirectory of the locale tree, generated by taking the basename of the file,
    removing the \t{.*} suffix, and appending \t{/LC_MESSAGES}\@. The name of the installed files
    is the package name with \t{.mo} appended. Failure behaviour is EAPI dependent as per
    section~\ref{sec:failure-behaviour}. The locale tree location is EAPI dependent as per
    table~\ref{tab:domo-path}.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.

\item[dosbin] As \t{dobin}, but installs to \t{DESTTREE/sbin}.

\item[dosym] Creates a symbolic link named as for its second parameter, pointing to the first.
    If the directory containing the new link does not exist, creates it.

    \featurelabel{dosym-relative} In EAPIs listed in table~\ref{tab:dosym-r} as supporting creation
    of relative paths, when called with option \t{-r}, the first parameter (the link target) is
    converted from an absolute path to a path relative to the the second parameter (the link name).
    The algorithm must return a result identical to the one returned by the function in
    listing~\ref{lst:dosym-r}, with \t{realpath} and \t{dirname} from GNU coreutils version~8.32.
    Specifying option \t{-r} together with a relative path as first (target) parameter is an error.

    Failure behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\begin{listing}[h]
\caption{Create a relative path for \t{dosym -r}} \label{lst:dosym-r}
\begin{verbatim}
dosym_relative_path() {
    local link=$(realpath -m -s "/${2#/}")
    local linkdir=$(dirname "${link}")
    realpath -m -s --relative-to="${linkdir}" "$1"
}
\end{verbatim}
\end{listing}

\item[fowners] Acts as for \t{chown}, but takes paths relative to the image directory. Failure
    behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[fperms] Acts as for \t{chmod}, but takes paths relative to the image directory. Failure
    behaviour is EAPI dependent as per section~\ref{sec:failure-behaviour}.

\item[keepdir] For each argument, creates a directory as for \t{dodir}, and an empty file whose
    name starts with \t{.keep} in that directory to ensure that the directory does not get removed
    by the package manager should it be empty at any point. Failure behaviour is EAPI dependent
    as per section~\ref{sec:failure-behaviour}.

\item[newbin] \featurelabel{newfoo-stdin} As for \t{dobin}, but takes two parameters. The first is
    the file to install; the second is the new filename under which it will be installed. In EAPIs
    specified by table~\ref{tab:newfoo-stdin-table}, standard input is read when the first
    parameter is \t{-} (a hyphen). In this case, it is an error if standard input is a terminal.

\item[newconfd] As for \t{doconfd}, but takes two parameters as for \t{newbin}.

\item[newdoc] As above, for \t{dodoc}.

\item[newenvd] As above, for \t{doenvd}.

\item[newexe] As above, for \t{doexe}.

\item[newheader] As above, for \t{doheader}.

\item[newinitd] As above, for \t{doinitd}.

\item[newins] As above, for \t{doins}.

\item[newlib.a] As above, for \t{dolib.a}.

\item[newlib.so] As above, for \t{dolib.so}.

\item[newman] As above, for \t{doman}.

\item[newsbin] As above, for \t{dosbin}.

\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting \t{dodoc -r}}
    \label{tab:dodoc-table}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Supports \t{dodoc -r}?}} \\
      \midrule
      0, 1, 2, 3        & No  \\
      4, 5, 6, 7, 8, 9  & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting \t{doheader} and \t{newheader}}
    \label{tab:doheader-table}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Supports \t{doheader} and \t{newheader}?}} \\
      \midrule
      0, 1, 2, 3, 4     & No  \\
      5, 6, 7, 8, 9     & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting symlinks for \t{doins}}
    \label{tab:doins-table}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{doins} supports symlinks?}} \\
      \midrule
      0, 1, 2, 3        & No  \\
      4, 5, 6, 7, 8, 9  & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{\t{doman} language support options for EAPIs}
    \label{tab:doman-table}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Language detection by filename?}} &
      \multicolumn{1}{c}{\textbf{Option \t{-i18n} takes precedence?}} \\
      \midrule
      0, 1              & No  & Not applicable \\
      2, 3              & Yes & No             \\
      4, 5, 6, 7, 8, 9  & Yes & Yes            \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting stdin for \t{new*} commands}
    \label{tab:newfoo-stdin-table}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{new*} can read from stdin?}} \\
      \midrule
      0, 1, 2, 3, 4     & No  \\
      5, 6, 7, 8, 9     & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{\t{domo} destination path in EAPIs}
    \label{tab:domo-path}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Destination path}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6 & \t{\$\{DESTTREE\}/share/locale} \\
      7, 8, 9             & \t{/usr/share/locale} \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting \t{dosym -r}}
    \label{tab:dosym-r}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{dosym} supports creation of relative paths?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6, 7  & No  \\
      8, 9                    & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Commands affecting install destinations}
The following commands are used to set the various destination trees and options used by the above
installation commands. They must be shell functions or aliases, due to the need to set variables
read by the above commands. Ebuilds must not run any of these commands once the current phase
function has returned.

\begin{description}

\item[into] Takes exactly one argument, and sets the value of \t{DESTTREE} for future invocations
    of the above utilities to it. Creates the directory under \t{\$\{ED\}} in offset-prefix aware
    EAPIs or under \t{\$\{D\}} in offset-prefix agnostic EAPIs, using \t{install -d} with no
    additional options, if it does not already exist. Failure behaviour is EAPI dependent as per
    section~\ref{sec:failure-behaviour}.

\item[insinto] As \t{into}, for \t{INSDESTTREE}.

\item[exeinto] As \t{into}, for install path of \t{doexe} and \t{newexe}.

\item[docinto] As \t{into}, for install subdirectory of \t{dodoc} et al.

\item[insopts] \featurelabel{insopts} Takes one or more arguments, and sets the options passed by
    \t{doins} et al.\ to the \t{install} command to them. Behaviour upon encountering empty
    arguments is undefined. Depending on EAPI, affects only those commands that are specified
    by table~\ref{tab:insopts-commands} as respecting \t{insopts}.

\item[diropts] As \t{insopts}, for \t{dodir} et al.

\item[exeopts] \featurelabel{exeopts} As \t{insopts}, for \t{doexe} et al. Depending on EAPI,
    affects only those commands that are specified by table~\ref{tab:exeopts-commands}
    as respecting \t{exeopts}.

\item[libopts] As \t{insopts}, for \t{dolib} et al.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as
    per section~\ref{sec:banned-commands}.

\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Commands respecting \t{insopts} for EAPIs}
    \label{tab:insopts-commands}
    \begin{tabular}{lllll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{doins}?}} &
      \multicolumn{1}{c}{\textbf{\t{doconfd}?}} &
      \multicolumn{1}{c}{\textbf{\t{doenvd}?}} &
      \multicolumn{1}{c}{\textbf{\t{doheader}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6, 7  & Yes & Yes & Yes & Yes \\
      8, 9                    & Yes & No  & No  & No  \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Commands respecting \t{exeopts} for EAPIs}
    \label{tab:exeopts-commands}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{doexe}?}} &
      \multicolumn{1}{c}{\textbf{\t{doinitd}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6, 7  & Yes & Yes \\
      8, 9                    & Yes & No  \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Commands controlling manipulation of files in the staging area}
These commands are used to control optional manipulations that the package manager may perform on
files in the staging directory \t{ED}, like compressing files or stripping symbols from object
files.

For each of the operations mentioned below, the package manager shall maintain an inclusion list
and an exclusion list, in order to control which directories and files the operation may or may not
be performed upon. The initial contents of the two lists is specified below for each of the
commands, respectively.

Any of these operations shall be carried out after \t{src_install} has completed, and before the
execution of any subsequent phase function. For each item in the inclusion list, pretend it has
the value of the \t{ED} variable prepended, then:

\begin{compactitem}
\item If it is a directory, act as if every file or directory immediately under this directory
    were in the inclusion list.
\item If the item is a file, the operation may be performed on it, unless it has been excluded as
    described below.
\item If the item does not exist, it is ignored.
\end{compactitem}

Whether an item is to be excluded is determined as follows: For each item in the exclusion list,
pretend it has the value of the \t{ED} variable prepended, then:

\begin{compactitem}
\item If it is a directory, act as if every file or directory immediately under this directory
    were in the exclusion list.
\item If the item is a file, the operation shall not be performed on it.
\item If the item does not exist, it is ignored.
\end{compactitem}

The package manager shall take appropriate steps to ensure that any operations that it performs on
files in the staging area behave sensibly even if an item is listed in the inclusion list multiple
times or if an item is a symlink.

\featurelabel{docompress} In EAPIs listed in table~\ref{tab:staging-area-commands} as supporting
controllable compression, the package manager may optionally compress a subset of the files under
the \t{ED} directory. The package manager shall ensure that its compression mechanisms do not
compress a file twice if it is already compressed using the same compressed file format.
For compression, the initial values of the two lists are as follows:

\begin{compactitem}
\item The inclusion list contains \t{/usr/share/doc}, \t{/usr/share/info} and \t{/usr/share/man}.
\item The exclusion list contains \t{/usr/share/doc/\$\{PF\}/html}.
\end{compactitem}

\featurelabel{dostrip} In EAPIs listed in table~\ref{tab:staging-area-commands} as supporting
controllable stripping of symbols, the package manager may strip a subset of the files under the
\t{ED} directory. For stripping of symbols, the initial values of the two lists are as follows:

\begin{compactitem}
\item If the \t{RESTRICT} variable described in section~\ref{sec:restrict} enables a \t{strip}
    token, the inclusion list is empty; otherwise it contains \t{/} (the root path).
\item The exclusion list is empty.
\end{compactitem}

The following commands may be used in \t{src_install} to alter these lists. It is an error to call
any of these functions from any other phase.

\begin{description}
\item[docompress] If the first argument is \t{-x}, add each of its subsequent arguments to the
    exclusion list for compression. Otherwise, add each argument to the respective inclusion list.
    Only available in EAPIs listed in table~\ref{tab:staging-area-commands} as supporting
    \t{docompress}.

\item[dostrip] If the first argument is \t{-x}, add each of its subsequent arguments to the
    exclusion list for stripping of symbols. Otherwise, add each argument to the respective
    inclusion list. Only available in EAPIs listed in table~\ref{tab:staging-area-commands} as
    supporting \t{dostrip}.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Commands controlling manipulation of files in the staging area in EAPIs}
    \label{tab:staging-area-commands}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{P{13.5em}}{\textbf{Supports controllable compression and \t{docompress}?}} &
      \multicolumn{1}{P{10.5em}}{\textbf{Supports controllable stripping and \t{dostrip}?}} \\
      \midrule
      0, 1, 2, 3        & No  & No  \\
      4, 5, 6           & Yes & No  \\
      7, 8, 9           & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{USE list functions}
These functions provide behaviour based upon set or unset use flags. Ebuilds must not run any of
these commands once the current phase function has returned.

Unless otherwise noted, if any of these functions is called with a flag value that is not included
in \t{IUSE_EFFECTIVE}, either behaviour is undefined or it is an error as decided by
table~\ref{tab:use-list-strictness}.

\begin{description}
\item[use] Returns shell true (0) if the first argument (a \t{USE} flag name) is enabled, false
    otherwise.  If the flag name is prefixed with \t{!}, returns true if the flag is disabled, and
    false if it is enabled. It is guaranteed that this command is quiet.
\item[usev] \featurelabel{usev} The same as \t{use}, but also prints the flag name if the condition
    is met. In EAPIs listed in table~\ref{tab:use-list-args} as supporting an optional second
    argument for \t{usev}, prints the second argument instead, if it is specified and if the
    condition is met.
\item[useq] Deprecated synonym for \t{use}.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.
\item[use_with] \featurelabel{use-with} Has one-, two-, and three-argument forms. The first
    argument is a USE flag name, the second a \t{configure} option name (\t{\$\{opt\}}), defaulting
    to the same as the first argument if not provided, and the third is a string value
    (\t{\$\{value\}}). For EAPIs listed in table~\ref{tab:use-list-args} as not supporting it,
    an empty third argument is treated as if it weren't provided. If the USE flag is set, outputs
    \t{-{}-with-\$\{opt\}=\$\{value\}} if the third argument was provided, and
    \t{-{}-with-\$\{opt\}} otherwise. If the flag is not set, then it outputs
    \t{-{}-without-\$\{opt\}}. The condition is inverted if the flag name is prefixed with~\t{!};
    this is valid only for the two- and three-argument forms.
\item[use_enable] Works the same as \t{use_with()}, but outputs \t{-{}-enable-} or
    \t{-{}-disable-} instead of \t{-{}-with-} or \t{-{}-without-}.
\item[usex] \featurelabel{usex} Accepts at least one and at most five arguments. The first argument
    is a USE flag name, any subsequent arguments (\t{\$\{arg2\}} to \t{\$\{arg5\}}) are string
    values. If not provided, \t{\$\{arg2\}} and \t{\$\{arg3\}} default to \t{yes} and \t{no},
    respectively; \t{\$\{arg4\}} and \t{\$\{arg5\}} default to the empty string. If the USE flag is
    set, outputs \t{\$\{arg2\}\$\{arg4\}}. Otherwise, outputs \t{\$\{arg3\}\$\{arg5\}}.
    The condition is inverted if the flag name is prefixed with~\t{!}.
    Only available in EAPIs listed in table~\ref{tab:use-list-functions} as supporting \t{usex}.
\item[in_iuse] \featurelabel{in-iuse} Returns shell true (0) if the first argument (a \t{USE} flag
    name) is included in \t{IUSE_EFFECTIVE}, false otherwise. Only available in EAPIs listed in
    table~\ref{tab:use-list-functions} as supporting \t{in_iuse}.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPI behaviour for use queries not in \t{IUSE_EFFECTIVE}}
    \label{tab:use-list-strictness}
    \begin{tabular}{ll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{Behaviour}} \\
      \midrule
      0, 1, 2, 3        & Undefined \\
      4, 5, 6, 7, 8, 9  & Error     \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{\t{usev}, \t{use_with} and \t{use_enable} arguments for EAPIs}
    \label{tab:use-list-args}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{P{8em}}{\textbf{\t{usev} has optional second argument?}} &
      \multicolumn{1}{P{14em}}{\textbf{\t{use_with} and \t{use_enable} support empty third
        argument?}} \\
      \midrule
      0, 1, 2, 3        & No  & No  \\
      4, 5, 6, 7        & No  & Yes \\
      8, 9              & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting \t{usex} and \t{in_iuse}}
    \label{tab:use-list-functions}
    \begin{tabular}{lll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{usex}?}} &
      \multicolumn{1}{c}{\textbf{\t{in_iuse}?}} \\
      \midrule
      0, 1, 2, 3, 4     & No  & No  \\
      5                 & Yes & No  \\
      6, 7, 8, 9        & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Text list functions}
These functions check a list of arguments for a particular value. They must be implemented
internally as shell functions and may be called in global scope.
\nobreakpar
\begin{description}
\item[has] Returns shell true (0) if the first argument (a word) is found in the list of subsequent
    arguments, false otherwise. Guaranteed quiet.
\item[hasv] The same as \t{has}, but also prints the first argument if found.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.
\item[hasq] Deprecated synonym for \t{has}.
    In EAPIs listed in table~\ref{tab:banned-commands-table}, this command is banned as per
    section~\ref{sec:banned-commands}.
\end{description}

\subsection{Version manipulation and comparison commands}
\featurelabel{ver-commands}
These commands provide utilities for working with version strings. They must all be implemented
internally as shell functions, i.\,e.\ they are callable in global scope. Availability of these
commands per EAPI is listed in table~\ref{tab:version-commands}.

For the purpose of version manipulation commands, the specification provides a method for splitting
an arbitrary version string (not necessarily conforming to section~\ref{sec:version-spec}) into
a series of version components and version separators.

In the context of this section, a \i{version component} consists either purely of digits
(\t{[0-9]+}) or purely of upper- and lower-case ASCII letters (\t{[A-Za-z]+}). A \i{version
separator} is either a string of any other characters (\t{[\textasciicircum A-Za-z0-9]+}), or it
occurs at the transition between a sequence of digits and a sequence of letters, or vice versa.
In the latter case, the version separator is an empty string.

The version string is processed left-to-right, with the successive version components being assigned
successive indices starting with 1. The separator following a version component is assigned
the index of the preceding version component. If the first version component is preceded by
a non-empty string of version separator characters, this separator is assigned the index 0.

The version components are presumed present if not empty. The version separators between version
components are always presumed present, even if they are empty. The version separators preceding
the first version component and following the last are only presumed present if they are not empty.

Whenever the commands support ranges, the range is specified as an unsigned integer, optionally
followed by a hyphen (\t{-}), which in turn is optionally followed by another unsigned integer.

A single integer specifies a single component or separator index. An integer followed by a hyphen
specifies all components or separators starting with the one at the specified index. Two integers
separated by a hyphen specify a range starting at the index specified by the first and ending at
the second, inclusively.

\begin{description}
\item[ver_cut] Takes a range as the first argument, and optionally a version string as the second.
    Prints a substring of the version string starting at the version component specified as start
    of the range and ending at the version component specified as end of the range. If the version
    string is not specified, \t{\$\{PV\}} is used.

    If the range spans outside the present version components, the missing components and separators
    are presumed empty. In particular, the range starting at zero includes the zeroth version
    separator if present, and the range spanning past the last version component includes the suffix
    following it if present. A range that does not intersect with any present version components
    yields an empty string.

\item[ver_rs] Takes one or more pairs of arguments, optionally followed by a version string.
    Every argument pair specifies a range and a replacement string. Prints a version string after
    performing the specified separator substitutions. If the version string is not specified,
    \t{\$\{PV\}} is used.

    For every argument pair specified, each of the version separators present at indices specified
    by the range is replaced with the replacement string, in order. If the range spans outside
    the range of present version separators, it is silently truncated.

\item[ver_test] Takes two or three arguments. In the 3-argument form, takes an LHS version string,
    followed by an operator, followed by an RHS version string. In the 2-argument form, the first
    version string is omitted and \t{\$\{PVR\}} is used as LHS version string. The operator can be
    \t{-eq} (equal to), \t{-ne} (not equal to), \t{-gt} (greater than), \t{-ge} (greater than or
    equal to), \t{-lt} (less than) or \t{-le} (less than or equal to). Returns shell true (0) if
    the specified relation between the LHS and RHS version strings is fulfilled.

    Both version strings must conform to the version specification in
    section~\ref{sec:version-spec}. Comparison is done using algorithm~\ref{alg:version-comparison}.

\item[ver_replacing] \featurelabel{ver-replacing} Takes an operator and a version string as
    arguments, which follow the same specification as in \t{ver_test}. Iterates over the elements
    of \t{REPLACING_VERSIONS}, using \t{ver_test} to compare each element against the version
    string. Returns shell true (0) if the specified relation holds for at least one element,
    shell false (1) otherwise. In particular, shell false is returned when \t{REPLACING_VERSIONS}
    is empty.

    Only available in EAPIs listed in table~\ref{tab:version-commands} as supporting
    \t{ver_replacing}. The command is only meaningful in phases where \t{REPLACING_VERSIONS} is
    defined.
\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{EAPIs supporting version manipulation commands}
    \label{tab:version-commands}
    \begin{tabular}{lllll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{ver_cut}?}} &
      \multicolumn{1}{c}{\textbf{\t{ver_rs}?}} &
      \multicolumn{1}{c}{\textbf{\t{ver_test}?}} &
      \multicolumn{1}{c}{\textbf{\t{ver_replacing}?}} \\
      \midrule
      0, 1, 2, 3, 4, 5, 6 & No  & No  & No  & No  \\
      7, 8                & Yes & Yes & Yes & No  \\
      9                   & Yes & Yes & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Misc commands}
The following commands are always available in the ebuild environment, but don't really fit in any
of the above categories. Ebuilds must not run any of these commands once the current phase function
has returned.

\begin{description}
\item[dosed] Takes any number of arguments, which can be files or \t{sed} expressions. For each
    argument, if it names, relative to \t{ED} (offset-prefix aware EAPIs) or \t{D} (offset-prefix
    agnostic EAPIs) a file which exists, then \t{sed} is run with the current expression on that
    file. Otherwise, the current expression is set to the text of the argument. The initial value
    of the expression is \t{s:\$\{ED\}::g} in offset-prefix aware EAPIs and \t{s:\$\{D\}::g} in
    offset-prefix agnostic EAPIs. In EAPIs listed in table~\ref{tab:banned-commands-table}, this
    command is banned as per section~\ref{sec:banned-commands}.

\item[unpack] Unpacks one or more source archives, in order, into the current directory.
    For compressed files, creates the target file in the current directory, with the compression
    suffix removed from its name. After unpacking, must ensure that all filesystem objects inside
    the current working directory (but not the current working directory itself) have permissions
    \t{a+r,u+w,go-w} and that all directories under the current working directory additionally have
    permissions \t{a+x}.

    Arguments to \t{unpack} are interpreted as follows:
    \begin{compactitem}
    \item A filename without path (i.\,e.\ not containing any slash) is looked up in \t{DISTDIR}.
    \item An argument starting with the string \t{./} is a path relative to the working directory.
    \item \featurelabel{unpack-absolute} Otherwise, for EAPIs listed in
        table~\ref{tab:unpack-behaviour} as supporting absolute and relative paths, the argument is
        interpreted as a literal path (absolute, or relative to the working directory); for EAPIs
        listed as \emph{not} supporting such paths, \t{unpack} shall abort the build process.
    \end{compactitem}

    Any unrecognised file format shall be skipped without raising an error. If unpacking a supported
    file format fails, \t{unpack} shall abort the build process.

    \featurelabel{unpack-extensions} Must be able to unpack the following file formats, if the
    relevant binaries are available:
    \begin{itemize}
    \item tar files (\t{*.tar}). Ebuilds must ensure that GNU tar is installed.
    \item gzip-compressed files (\t{*.gz, *.z, *.Z}). Ebuilds must ensure that GNU gzip is
        installed.
    \item gzip-compressed tar files (\t{*.tar.gz, *.tgz, *.tar.z, *.tar.Z}). Ebuilds must ensure
        that GNU gzip and GNU tar are installed.
    \item bzip2-compressed files (\t{*.bz2, *.bz}). Ebuilds must ensure that bzip2 is installed.
    \item bzip2-compressed tar files (\t{*.tar.bz2, *.tbz2, *.tar.bz, *.tbz}). Ebuilds must ensure
        that bzip2 and GNU tar are installed.
    \item zip files (\t{*.zip, *.ZIP, *.jar}). Ebuilds must ensure that Info-ZIP Unzip is installed.
    \item 7zip files (\t{*.7z, *.7Z}). Ebuilds must ensure that P7ZIP is installed. Only for EAPIs
        listed in table~\ref{tab:unpack-extensions-table} as supporting \t{.7z}.
    \item rar files (\t{*.rar, *.RAR}). Ebuilds must ensure that RARLAB's unrar is installed.
        Only for EAPIs listed in table~\ref{tab:unpack-extensions-table} as supporting \t{.rar}.
    \item LHA archives (\t{*.LHA, *.LHa, *.lha, *.lzh}). Ebuilds must ensure that the lha program is
        installed. Only for EAPIs listed in table~\ref{tab:unpack-extensions-table} as supporting
        \t{.lha}.
    \item ar archives (\t{*.a}). Ebuilds must ensure that GNU binutils is installed.
    \item deb packages (\t{*.deb}). Ebuilds must ensure that the deb2targz program is installed on
        those platforms where the GNU binutils ar program is not available and the installed ar
        program is incompatible with GNU archives. Otherwise, ebuilds must ensure that GNU binutils
        is installed.
    \item lzma-compressed files (\t{*.lzma}). Ebuilds must ensure that XZ Utils is installed.
    \item lzma-compressed tar files (\t{*.tar.lzma}). Ebuilds must ensure that XZ Utils and GNU tar
        are installed.
    \item xz-compressed files (\t{*.xz}). Ebuilds must ensure that XZ Utils is installed. Only for
        EAPIs listed in table~\ref{tab:unpack-extensions-table} as supporting \t{.xz}.
    \item xz-compressed tar files (\t{*.tar.xz, *.txz}). Ebuilds must ensure that XZ Utils and
        GNU tar are installed. Only for EAPIs listed in table~\ref{tab:unpack-extensions-table} as
        supporting \t{.tar.xz} or \t{.txz}.
    \end{itemize}
    It is up to the ebuild to ensure that the relevant external utilities are available, whether by
    being in the system set or via dependencies.

    \featurelabel{unpack-ignore-case} \t{unpack} matches filename extensions in a case-insensitive
    manner, for EAPIs listed such in table~\ref{tab:unpack-behaviour}.

    \ChangeWhenAddingAnEAPI{9}
    \begin{centertable}{\t{unpack} behaviour for EAPIs}
        \label{tab:unpack-behaviour}
        \begin{tabular}{lll}
          \toprule
          \multicolumn{1}{c}{\textbf{EAPI}} &
          \multicolumn{1}{c}{\textbf{Supports absolute and relative paths?}} &
          \multicolumn{1}{c}{\textbf{Case-insensitive matching?}} \\
          \midrule
          0, 1, 2, 3, 4, 5  & No  & No  \\
          6, 7, 8, 9        & Yes & Yes \\
          \bottomrule
        \end{tabular}
    \end{centertable}

    \ChangeWhenAddingAnEAPI{9}
    \begin{centertable}{\t{unpack} extensions for EAPIs}
        \label{tab:unpack-extensions-table}
        \begin{tabular}{llllllll}
          \toprule
          \multicolumn{1}{c}{\textbf{EAPI}} &
          \multicolumn{1}{c}{\textbf{\t{.xz}?}} &
          \multicolumn{1}{c}{\textbf{\t{.tar.xz}?}} &
          \multicolumn{1}{c}{\textbf{\t{.txz}?}} &
          \multicolumn{1}{c}{\textbf{\t{.7z}?}} &
          \multicolumn{1}{c}{\textbf{\t{.rar}?}} &
          \multicolumn{1}{c}{\textbf{\t{.lha}?}} \\
          \midrule
          0, 1, 2           & No  & No  & No  & Yes & Yes & Yes \\
          3, 4, 5           & Yes & Yes & No  & Yes & Yes & Yes \\
          6, 7              & Yes & Yes & Yes & Yes & Yes & Yes \\
          8, 9              & Yes & Yes & Yes & No  & No  & No  \\
          \bottomrule
        \end{tabular}
    \end{centertable}

\item[inherit] See section~\ref{sec:inherit}.

\item[default]
    \featurelabel{default-func} Calls the \t{default_} function for the current phase (see
    section~\ref{sec:default-phase-funcs}). Must not be called if the \t{default_} function does
    not exist for the current phase in the current EAPI\@. Only available in EAPIs listed in
    table~\ref{tab:misc-commands} as supporting \t{default}.

\item[einstalldocs] \featurelabel{einstalldocs} Takes no arguments. Installs the files specified
    by the \t{DOCS} and \t{HTML_DOCS} variables or a default set of files, according to
    algorithm~\ref{alg:einstalldocs}. If called using \t{nonfatal} and any of the called commands
    returns a non-zero exit status, returns immediately with the same exit status. Only available
    in EAPIs listed in table~\ref{tab:misc-commands} as supporting \t{einstalldocs}.

\begin{algorithm}
\caption{\t{einstalldocs} logic} \label{alg:einstalldocs}
\begin{algorithmic}[1]
\STATE save the value of the install directory for \t{dodoc}
\STATE set the install directory for \t{dodoc} to \t{/usr/share/doc/\$\{PF\}}
\IF{the DOCS variable is a non-empty array}
    \STATE call \t{dodoc -r "\$\{DOCS[@]\}"}
\ELSIF{the DOCS variable is a non-empty scalar}
    \STATE call \t{dodoc -r \$\{DOCS\}}
\ELSIF{the DOCS variable is unset}
    \FORALL{$d$ matching the filename expansion of \t{README*} \t{ChangeLog} \t{AUTHORS} \t{NEWS}
            \t{TODO} \t{CHANGES} \t{THANKS} \t{BUGS} \t{FAQ} \t{CREDITS} \t{CHANGELOG}}
        \IF{file $d$ exists and has a size greater than zero}
            \STATE call \t{dodoc} with $d$ as argument
        \ENDIF
    \ENDFOR
\ENDIF
\STATE set the install directory for \t{dodoc} to \t{/usr/share/doc/\$\{PF\}/html}
\IF{the HTML_DOCS variable is a non-empty array}
    \STATE call \t{dodoc -r "\$\{HTML_DOCS[@]\}"}
\ELSIF{the HTML_DOCS variable is a non-empty scalar}
    \STATE call \t{dodoc -r \$\{HTML_DOCS\}}
\ENDIF
\STATE restore the value of the install directory for \t{dodoc}
\RETURN shell true (0)
\end{algorithmic}
\end{algorithm}

\item[get_libdir] \featurelabel{get-libdir} Prints the libdir name obtained according to
    algorithm~\ref{alg:get-libdir}. Must be implemented internally as a shell function and may be
    called in global scope. Only available in EAPIs listed in table~\ref{tab:misc-commands} as
    supporting \t{get_libdir}.

\begin{algorithm}
\caption{Library directory logic} \label{alg:get-libdir}
\begin{algorithmic}[1]
\STATE let libdir=\t{lib}
\IF{the ABI environment variable is set}
    \STATE let libvar=LIBDIR_\$ABI
    \IF{the environment variable named by libvar is set}
        \STATE let libdir=the value of the variable named by libvar
    \ENDIF
\ENDIF
\RETURN the value of libdir
\end{algorithmic}
\end{algorithm}

\item[edo] \featurelabel{edo} Takes a command line, prints it to stderr and executes the command.
Specifically, the entire list of (one or more) arguments is output as an informational message
to stderr; individual tokens may be reformatted to avoid ambiguity. The first argument is then
executed as a command, with the remaining arguments passed to it. If the command fails, \t{edo}
aborts the build process using \t{die}, unless it was called under \t{nonfatal}, in which case it
returns a non-zero exit status.

\t{edo} must be implemented internally as a shell function. Only available in EAPIs listed in
table~\ref{tab:misc-commands} as supporting \t{edo}.

\end{description}

\ChangeWhenAddingAnEAPI{9}
\begin{centertable}{Misc commands for EAPIs}
    \label{tab:misc-commands}
    \begin{tabular}{lllll}
      \toprule
      \multicolumn{1}{c}{\textbf{EAPI}} &
      \multicolumn{1}{c}{\textbf{\t{default}?}} &
      \multicolumn{1}{c}{\textbf{\t{einstalldocs}?}} &
      \multicolumn{1}{c}{\textbf{\t{get_libdir}?}} &
      \multicolumn{1}{c}{\textbf{\t{edo}?}} \\
      \midrule
      0, 1              & No  & No  & No  & No  \\
      2, 3, 4, 5        & Yes & No  & No  & No  \\
      6, 7, 8           & Yes & Yes & Yes & No  \\
      9                 & Yes & Yes & Yes & Yes \\
      \bottomrule
    \end{tabular}
\end{centertable}

\subsection{Debug commands}
The following commands are available for debugging. Normally all of these commands should be no ops;
a package manager may provide a special debug mode where these commands instead do something.
These commands must be implemented internally as shell functions and may be called in global scope.
Ebuilds must not run any of these commands once the current phase function has returned.

\begin{description}
\item[debug-print] If in a special debug mode, the arguments should be outputted or recorded using
    some kind of debug logging.
\item[debug-print-function] Calls \t{debug-print} with \t{\$1: entering function} as the first
    argument and the remaining arguments as additional arguments.
\item[debug-print-section] Calls \t{debug-print} with \t{now in section \$*}.
\end{description}

\subsection{Reserved commands and variables}

Except where documented otherwise, all functions and variables that begin with any of the following
strings (ignoring case) are reserved for package manager use and may not be used or relied upon by
ebuilds:

\begin{compactitem}
\item \t{__} (two underscores)
\item \t{abort}
\item \t{dyn}
\item \t{prep}
\end{compactitem}

The same applies to functions and variables that contain any of the following strings (ignoring
case):
\nobreakpar
\begin{compactitem}
\item \t{ebuild} (unless immediately preceded by another letter)
\item \t{hook}
\item \t{paludis}
\item \t{portage}
\end{compactitem}

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