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environ(7)           BSD Miscellaneous Information Manual           environ(7)


NAME

     environ -- user environment


SYNOPSIS

     extern char **environ;


DESCRIPTION

     An array of strings called the environment is made available by execve(2)
     when a process begins.  By convention these strings have the form
     ``name=value''.  The following names are used by various commands:

     BLOCKSIZE  The size of the block units used by several commands, most
                notably df(1), du(1) and ls(1).  BLOCKSIZE may be specified in
                units of a byte by specifying a number, in units of a kilobyte
                by specifying a number followed by ``K'' or ``k'', in units of
                a megabyte by specifying a number followed by ``M'' or ``m''
                and in units of a gigabyte by specifying a number followed by
                ``G'' or ``g''.  Sizes less than 512 bytes or greater than a
                gigabyte are ignored.

     EXINIT     A startup list of commands read by ex(1) and vi(1).

     HOME       A user's login directory, set by login(1) from the password
                file passwd(5).

     PATH       The sequence of directories, separated by colons, searched by
                csh(1), sh(1), system(3), execvp(3), etc, when looking for an
                executable file.  PATH is set to ``/usr/bin:/bin'' initially
                by login(1).

     PRINTER    The name of the default printer to be used by lpr(1), lpq(1),
                and lprm(1).

     SHELL      The full pathname of the user's login shell.

     TERM       The kind of terminal for which output is to be prepared.  This
                information is used by commands, such as nroff(1) which may
                exploit special terminal capabilities.  See termcap(3) and
                terminfo(5).

     TMPDIR     The directory in which to store temporary files.  Most appli-
                cations use either ``/tmp'' or ``/var/tmp''.  Setting this
                variable will make them use another directory.

     TZ         The timezone to use when displaying dates.  The normal format
                is a pathname relative to ``/usr/share/zoneinfo''.  For exam-
                ple, the command ``env TZ=US/Pacific date'' displays the cur-
                rent time in California.  See tzset(3) for more information.

     LOGNAME    The login name of the user.

     USER       Deprecated synonym of LOGNAME (for backwards compatibility).

     Further names may be placed in the environment by the export command and
     name=value arguments in sh(1), or by the setenv command if you use
     csh(1).  It is unwise to change certain sh(1) variables that are fre-
     quently exported by .profile files, such as MAIL, PS1, PS2, and IFS,
     unless you know what you are doing.


PROGRAMMING

     Programs can query and modify the environment, using the environment rou-
     tines getenv(3), putenv(3), setenv(3) and unsetenv(3).  Direct access can
     be made through the global variable environ, though it is recommended
     that changes to the enviroment still be made through the environment rou-
     tines.

     Shared libraries and bundles don't have direct access to environ, which
     is only available to the loader ld(1) when a complete program is being
     linked.  The environment routines can still be used, but if direct access
     to environ is needed, the _NSGetEnviron() routine, defined in
     <crt_externs.h>, can be used to retrieve the address of environ at run-
     time.


SEE ALSO

     csh(1), ex(1), login(1), sh(1), getenv(3), putenv(3), setenv(3),
     unsetenv(3), execve(2), execle(3), system(3), termcap(3), terminfo(5)


HISTORY

     The environ manual page appeared in 4.2BSD.

4.2 Berkeley Distribution       April 19, 1994       4.2 Berkeley Distribution

Mac OS X 10.9 - Generated Thu Oct 17 05:45:07 CDT 2013
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