1ENVIRON(7)                 Linux Programmer's Manual                ENVIRON(7)
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NAME

6       environ - user environment
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SYNOPSIS

9       extern char **environ;
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DESCRIPTION

12       The  variable  environ points to an array of pointers to strings called
13       the "environment".  The last pointer in this array has the value  NULL.
14       (This variable must be declared in the user program, but is declared in
15       the header file <unistd.h> if the _GNU_SOURCE  feature  test  macro  is
16       defined.)   This  array  of strings is made available to the process by
17       the exec(3) call that started the process.  When  a  child  process  is
18       created via fork(2), it inherits a copy of its parent's environment.
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20       By  convention the strings in environ have the form "name=value".  Com‐
21       mon examples are:
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23       USER   The name of the logged-in user (used by  some  BSD-derived  pro‐
24              grams).
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26       LOGNAME
27              The  name  of  the logged-in user (used by some System-V derived
28              programs).
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30       HOME   A user's login directory, set by login(1) from the password file
31              passwd(5).
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33       LANG   The name of a locale to use for locale categories when not over‐
34              ridden by LC_ALL or more specific environment variables such  as
35              LC_COLLATE,  LC_CTYPE, LC_MESSAGES, LC_MONETARY, LC_NUMERIC, and
36              LC_TIME (see locale(7) for further details of the LC_*  environ‐
37              ment variables).
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39       PATH   The  sequence  of  directory  prefixes that sh(1) and many other
40              programs apply in searching for a file known  by  an  incomplete
41              pathname.   The  prefixes  are separated by ':'.  (Similarly one
42              has CDPATH used by some shells to find the target  of  a  change
43              directory  command, MANPATH used by man(1) to find manual pages,
44              and so on)
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46       PWD    The current working directory.  Set by some shells.
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48       SHELL  The pathname of the user's login shell.
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50       TERM   The terminal type for which output is to be prepared.
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52       PAGER  The user's preferred utility to display text files.
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54       EDITOR/VISUAL
55              The user's preferred utility to edit text files.
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57       Names may be placed in the shell's environment by the export command in
58       sh(1), or by the setenv command if you use csh(1).
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60       The initial environment of the shell is populated in various ways, such
61       as definitions from /etc/environment that are processed  by  pam_env(8)
62       for  all users at login time (on systems that employ pam(8)).  In addi‐
63       tion, various shell initialization scripts,  such  as  the  system-wide
64       /etc/profile  script  and  per-user