environ(5) — Macro Packages and Conventions
NAME
environ − User environment
SYNOPSIS
extern char ∗∗environ;
DESCRIPTION
An array of strings called the environment is made available by the execve() function when a process begins. By convention these strings have the form name=value. The following names are used by various commands:
EXINIT
A startup list of commands read by ex, edit, and vi.
HOME
A user’s login directory, set by login from the password file passwd.
PATH
The sequence of directories, separated by colons, searched by csh, sh, system, execvp, etc, when looking for an executable file. PATH is set to :/usr/ucb:/bin:/usr/bin initially by login.
PRINTER
The name of the default printer to be used by lpr, lpq, and lprm.
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 .\" See /usr/share/misc/termcap for a list of terminal types. .\"from TP " .\" Bold under TP !" -->
TERMCAP
The string describing the terminal in the TERM environment variable, or, if it begins with a / (slash), the name of the termcap file. See TERMPATH below.
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 TERMPATH is equivalent to a TERMPATH of $HOME/.termcap:/etc/termcap. TERMPATH is ignored if TERMCAP contains a full pathname.
USER
The login name of the user.
Further names may be placed in the environment by the export command and name=value arguments in sh, or by the setenv command if you use csh. It is unwise to change certain sh variables that are frequently exported by .profile files, such as MAIL, PS1, PS2, and IFS.