extern char **environ
An array of strings called the “environment” is made available by
when a process
begins. By convention these strings have the form
. The following
variables are recognized by various commands:
- The size of the block units used by several commands, most notably
ls(1). 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’, or 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.
- A list of startup commands read by
- The user's login directory, set by
login(1) from the password
- The login name of the user.
- The sequence of directories, separated by colons, searched by
execvp(3), etc. when
looking for an executable file. Initially set to the value of
/usr/bin:/bin, but expanded to include
- The name of the default printer to be used by
- The current working directory.
- The full pathname of the user's login shell.
- The kind of terminal for which output is to be prepared. This information
is used by commands such as
mandoc(1) which may exploit
special terminal capabilities. See
(termcap(5)) for a list of
- The string describing the terminal in
TERM, or, if
it begins with a ‘
/’, the name of
the termcap file. See
- A sequence of pathnames of termcap files, separated by colons or spaces,
which are searched for terminal descriptions in the order listed. Having
TERMPATH is equivalent to a
TERMPATH is ignored if
TERMCAP contains a full pathname.
- The directory in which to store temporary files. Most applications use
either /tmp or /var/tmp.
Setting this variable will make them use another directory.
- The time zone to use when displaying dates. The normal format is a
pathname relative to /usr/share/zoneinfo. For
example, the command
env TZ=US/Pacific date
displays the current time in California. See
tzset(3) for more
- Deprecated synonym of
LOGNAME (for backwards
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
frequently exported by .profile files, such as
IFS, unless you
know what you are doing.
The current environment variables can be printed with
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