ENVIRON(5) ENVIRON(5)
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:
CFTIME The default format string to be used by the
date(1) command and the ascftime() and cftime()
routines (see ctime(3C)). If CFTIME is not set
or is null, the default format string specified
in the /lib/cftime/LANGUAGE file (if it exists)
is used in its place (see cftime(4)).
CHRCLASS A value that corresponds to a file in
/lib/chrclass containing character
classification and conversion information. This
information is used
by commands (such as cat(1), ed(1), sort(1),
etc.) to classify characters as alphabetic,
printable, upper case, etc. and to convert
characters to upper or lower case.
When a program or command begins execution, the
tables containing this information are
initialized based on the value of CHRCLASS. If
CHRCLASS is non-existent, null, set to a value
for which no file exists in /lib/chrclass, or
errors occur while reading the file, the ASCII
character set is used. During execution, a
program or command can change the values in
these tables by calling the setchrclass()
routine. For more detail, see ctype(3C).
These tables are created using the chrtbl(1M)
command.
HOME The name of the user's login directory, set by
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login(1) from the password file (see passwd(4)).
LANGUAGE A language for which a printable file by that
name exists in /lib/cftime. This information is
used by commands (such as date(1), ls(1),
sort(1), etc.) to print date and time
information in the language specified.
If LANGUAGE is non-existent, null, set to a
value for which no file exists in /lib/cftime,
or errors occur while reading the file, the last
language requested will be used. (If no
language has been requested, the language
usaenglish is assumed.) For a description of
the content of files in /lib/cftime, see
cftime(4).
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. (For more
detail, see the "Execution" section of the sh(1)
manual page.)
TERM The kind of terminal for which output is to be
prepared. This information is used by commands,
such as mm(1) or vi(1), which may exploit
special capabilities of that terminal.
TZ Time zone information. The simplest format is
xxxnzzz where xxx is the standard local time
zone abbreviation, n is the difference in hours
from GMT (Greenwich Mean Time), and zzz is the
abbreviation for an alternate time zone (usually
the daylight-saving local time zone), if any;
for example,
TZ="EST5EDT"
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The most complex format allows you to specify
the difference in hours of the alternate time
zone from GMT and the starting day and time and
ending day and time for using this alternate
time zone. For example, in 1985 the complex
format corresponding to the above simple example
is:
TZ="EST5:00:00EDT4:00:00;118/2:00:00,300/2:00:00"
When the above complex format is used, it must
be surrounded by double quotes. For more
details, see ctime(3C) and timezone(4).
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 (see profile(4)).
NOTES
References to the cftime(4), ctime(3C), and ctype(3C) manual
pages refer to programming capabilities available beginning
with Issue 4.1 of the C Programming Language Utilities.
Administrators should note the following: if you attempt to
set the current date to one of the dates that the standard
and alternate time zones change (for example, the date that
daylight time is starting or ending), and you attempt to set
the time to a time in the interval between the end of
standard time and the beginning of the alternate time (or
the end of the alternate time and the beginning of standard
time), the results are unpredictable.
SEE ALSO
chrtbl(1M), cftime(4), passwd(4), profile(4), timezone(4),
in the System Administrator's Reference Manual.
exec(2), ctime(3C), ctype(3C) in the Programmer's Reference
Manual.
cat(1), date(1), ed(1), env(1), ls(1), login(1), nice(1),
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nohup(1), sh(1), sort(1), time(1), vi(1) in the User's
Reference Manual.
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