ENVIRON(5) INTERACTIVE UNIX System 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 classifica-
tion and conversion information. This informa-
tion is used by commands (such as cat(1), ed(1),
sort(1), etc.) to classify characters as alpha-
betic, printable, uppercase, etc., and to con-
vert characters to uppercase or lowercase.
When a program or command begins execution, the
tables containing this information are initial-
ized based on the value of CHRCLASS. If
CHRCLASS is nonexistent, 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 pro-
gram 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
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 informa-
tion in the language specified.
If LANGUAGE is nonexistent, 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
usa_english is assumed.) For a description of
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ENVIRON(5) INTERACTIVE UNIX System ENVIRON(5)
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 spe-
cial 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"
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 vari-
ables that are frequently exported by .profile files: MAIL,
PS1, PS2, IFS [see profile(4)].
SEE ALSO
exec(2), ctime(3C), ctype(3C), cftime(4), passwd(4), pro-
file(4), timezone(4).
cat(1), date(1), ed(1), env(1), ls(1), login(1), nice(1),
nohup(1), sh(1), sort(1), time(1), vi(1), chrtbl(1M) in the
INTERACTIVE UNIX System User's/System Administrator's Refer-
ence Manual.
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ENVIRON(5) INTERACTIVE UNIX System ENVIRON(5)
mm(1) in the DOCUMENTER'S WORKBENCH Software Release 2.0
Technical Discussion and Reference Manual.
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 stan-
dard 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.
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