NAME

environ − user environment

DESCRIPTION

An array of strings called the "environment" is made available by exec(2) when a process begins. By convention, these strings have the form "name=value". The following names are used by various commands:

PATH The sequence of directory prefixes that sh(1), time(1), nice(1), nohup(1), etc., apply in searching for a file known by an incomplete path name. The prefixes are separated by colons (:). Login(1) sets PATH=:/bin:/usr/bin .

HOME Name of the user’s login directory, set by login(1) From the password file, see passwd(4).

TERM The kind of terminal for which output is to be prepared.  This information is used by commands, such as mm(1) or tplot(1), that can exploit special capabilities of that terminal.

TZ Time zone information. The minimum format is tznamediff where tzname is an "alphabetic" string giving the time zone name or abbreviation, and diff is the difference in hours from GMT.  Diff may be positive (west of Greenwich) or negative (east of Greenwich).  Fractional hours are indicated as minutes preceded by a colon.  If a summer time zone adjustment (such as Daylight Savings in the US) is to be applied the format is tznamediffdstzname where dstzname is the name of the "Daylight Savings" time zone.  The entire string is compared with entries in the tztab file to determine the details of the time zone adjustment that should be applied, see tztab(4).

LANG Language selection. This is one of the names listed in langid(5). It is used to select the character set, lexical order, up and down shift tables, and other information that varies from one area to another.

Further names may be placed in the environment by the export command and "name=value" arguments in sh(1), or by exec(2). It is unwise to conflict with certain shell variables that are frequently exported by .profile files: MAIL , PS1 , PS2 , IFS . 

A process’s environment is accessible from C via the global variable:

char **environ;

that points to an array of pointers to the strings which comprise the environment.  The array is terminated by a null pointer. 

AUTHOR

Environ was developed by AT&T and HP. 

SEE ALSO

env(1), login(1), sh(1), exec(2), ctime(3C), getenv(3C), profile(4), term(5), tztab(4). 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021