.\" $NetBSD: environ.7,v 1.4 1995/07/03 19:45:07 jtc Exp $ .\" .\" Copyright (c) 1983, 1990, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)environ.7 8.3 (Berkeley) 4/19/94 .\" .Dd April 19, 1994 .Dt ENVIRON 7 .Os BSD 4.2 .Sh NAME .Nm environ .Nd user environment .Sh SYNOPSIS .Ar extern char **environ ; .Sh DESCRIPTION An array of strings called the .Ar environment is made available by .Xr execve 2 when a process begins. By convention these strings have the form .Dq Ar name=value . The following names are used by various commands: .Bl -tag -width BLOCKSIZE .It Ev BLOCKSIZE The size of the block units used by several commands, most notably .Xr df 1 , .Xr du 1 and .Xr 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. .It Ev EXINIT A startup list of commands read by .Xr ex 1 , .Xr edit 1 , and .Xr vi 1 . .It Ev HOME A user's login directory, set by .Xr login 1 from the password file .Xr passwd 5 . .It Ev PATH The sequence of directories, separated by colons, searched by .Xr csh 1 , .Xr sh 1 , .Xr system 3 , .Xr execvp 3 , etc, when looking for an executable file. PATH is set to ``/usr/bin:/bin'' initially by .Xr login 1 . .It Ev PRINTER The name of the default printer to be used by .Xr lpr 1 , .Xr lpq 1 , and .Xr lprm 1 . .It Ev SHELL The full pathname of the user's login shell. .It Ev TERM The kind of terminal for which output is to be prepared. This information is used by commands, such as .Xr nroff 1 or .Xr plot 1 which may exploit special terminal capabilities. See .Pa /usr/share/misc/termcap .Pq Xr termcap 5 for a list of terminal types. .It Ev TERMCAP The string describing the terminal in TERM, or, if it begins with a '/', the name of the termcap file. See .Ev TERMPATH below, .Xr termcap 5 , and .Xr termcap . .It Ev TERMPATH A sequence of pathnames of termcap files, separated by colons or spaces, which are searched for terminal descriptions in the order listed. Having no .Ev TERMPATH is equivalent to a .Ev TERMPATH of .Dq Pa $HOME/.termcap:/etc/termcap . .Ev TERMPATH is ignored if .Ev TERMCAP contains a full pathname. .It Ev TMPDIR The directory in which to store temporary files. Most applications use either .Dq /tmp or .Dq /var/tmp . Setting this variable will make them use another directory. .It Ev TZ The timezone to use when displaying dates. The normal format is a pathname relative to .Dq /usr/share/zoneinfo . For example, the command .Dq env TZ=US/Pacific date displays the current time in California. See .Xr tzset 3 for more information. .It Ev LOGNAME The login name of the user. .It Ev USER Deprecated synonym of .Ev LOGNAME (for backwards compatibility). .El .Pp Further names may be placed in the environment by the .Xr export command and .Ar name=value arguments in .Xr sh 1 , or by the .Xr setenv command if you use .Xr csh 1 . It is unwise to change certain .Xr sh 1 variables that are frequently exported by .Pa .profile files, such as .Ev MAIL , .Ev PS1 , .Ev PS2 , and .Ev IFS , unless you know what you are doing. .Sh PROGRAMMING Programs can query and modify the environment, using the environment routines .Xr getenv 3 , .Xr putenv 3 , .Xr setenv 3 and .Xr unsetenv 3 . Direct access can be made through the global variable .Va environ , though it is recommended that changes to the enviroment still be made through the environment routines. .Pp Shared libraries and bundles don't have direct access to .Va environ , which is only available to the loader .Xr ld 1 when a complete program is being linked. The environment routines can still be used, but if direct access to .Va environ is needed, the .Fn _NSGetEnviron routine, defined in .In crt_externs.h , can be used to retrieve the address of .Va environ at runtime. .Sh SEE ALSO .Xr csh 1 , .Xr ex 1 , .Xr login 1 , .Xr sh 1 , .Xr getenv 3 , .Xr putenv 3 , .Xr setenv 3 , .Xr unsetenv 3 , .Xr execve 2 , .Xr execle 3 , .Xr system 3 , .Xr termcap 3 , .Xr termcap 5 .Sh HISTORY The .Nm environ manual page appeared in .Bx 4.2 .