ENVIRON(5) ENVIRON(5)
NAME
environ - user environment
SYNOPSIS
extern char **environ;
DESCRIPTION
An array of strings called the `environment' is made avail-
able by exec(2) when a process begins. By convention these
strings have either the form name=value, defining a vari-
able, or name(){value}, defining a function; see sh(1). The
following variables are used by various commands:
PATH The sequence of directory prefixes that sh,
time(1), nice(1), etc., apply in searching for a
file known by an incomplete path name. The pre-
fixes are separated by `:'. Login(8) sets
`PATH=:/bin:/usr/bin'.
HOME A user's login directory, set by login(8) from the
password file passwd(5).
TERM The kind of terminal for which output is to be pre-
pared. This information is used by commands, such
as nroff or plot(1), which may exploit special ter-
minal capabilities. Some customary values of TERM
are 2621 (HP), 4014 (Tektronix), 5620 (Teletype),
and 630 (Teletype). See described in termcap(5),
for a longer list.
SHELL The name of the login shell.
The environment may be queried by getenv(3) or by the `set'
or `whatis' commands of sh(1). Names may be placed in the
environment by the `export' command and by name=value argu-
ments of sh(1). Names may also be placed in the environment
at the point of an exec(2). It is unwise to conflict with
certain sh(1) variables that are frequently exported by
files: MAIL, PS1, PS2, IFS.
SEE ALSO
sh(1), printenv(1), exec(2), getenv(3), term(6)
BUGS
Function definitions in the environment break some old pro-
grams, including old shells.