ENVIRON(M) XENIX System V ENVIRON(M)
Name
environ - The user environment.
Description
The user environment is a collection of information about a
user, such as his login directory, mailbox, and terminal
type. The environment is stored in special ``environment
variables,'' which can be assigned character values, such as
names of files, directories, and terminals. These variables
are automatically made available to programs and commands
invoked by the user. The commands can then use the values
to access the user's files and terminal.
The following is a short list of commonly used environment
variables.
PATH Defines the search path for the directories
containing commands. The system searches these
directories whenever a user types a command
without giving a full pathname. The search path
is one or more directory names separated by
colons (:). Initially, PATH is set to
:/bin:/usr/bin.
HOME Names the user's login directory. Initially,
HOME is set to the login directory given in the
user's passwd file entry.
TERM Defines the type of terminal being used. This
information is used by commands such as more(C)
which rely on information about the capabilities
of the user's terminal. The variable may be set
to any valid terminal name (see terminals(M))
directly or by using the tset(C) command.
TZ Defines time zone information. This information
is used by date(C) to display the appropriate
time. The variable may have any value of the
form:
xxxnzzzs; start/time, end/time
where xxx is standard local time zone
abbreviation (1-9 characters), n is the standard
time zone difference from GMT, and may be given
as hh:mm:ss (hours:minutes:seconds), zzz is the
summertime local time zone abbreviation of 1-9
characters (if any), s is the summertime time
zone difference from GMT, and may be given as
hh:mm:ss (hours:minutes:seconds), start and end
specify the day to begin and end summertime
based on one of four rules, and time is the time
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ENVIRON(M) XENIX System V ENVIRON(M)
of day the change to or from summertime occurs.
The rules for specifying start and end are:
Jn 1 based Julian day n
n 0 based Julian day n
Wn.d nth day of week d
Mm.n.d nth day of week d in month m
For example:
EST5:00:00EDT4:00:00;M4.1.0/2:00:00,M10.5.0/2:00:00.
Refer to the tz(M) manual page for more on TZ.
HZ Defines, with a numerical value, the number of
clock interrupts per second. The value of this
variable is dependent on the hardware, and
configured in the file etc/default/login. If HZ
is not defined, programs which depend on this
hertz value, such as prof(CP) and times(S), will
not run.
LANG Defines the language locale a user wishes to
use. This variable can be queried by
applications and utilities to determine how to
display information, what language to use for
messages, sorting order, and other language
dependent functions.
The environment can be changed by assigning a new value to a
variable. For Bourne shell, sh(C), an assignment has the
following format:
name=value
For example, the assignment:
TERM=h29
sets the TERM variable to the value ``h29''. The new value
can be ``exported'' to each subsequent invocation of a shell
by exporting the variable with the export command (see
sh(C)) or by using the env(C) command.
C-shell users make assignments using the setenv command.
For example:
setenv TERM h29
For more information, see csh(C).
A user may also add variables to the environment, but must
be sure that the new names do not conflict with exported
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shell variables such as MAIL, PS1, PS2, and IFS. Placing
assignments in the .profile file is a useful way to change
the environment automatically before a session begins. C-
shell users can place assignments in their .cshrc or .login
files.
Note that the environment is made available to all programs
as a string of arrays. Each string has the format:
name=value
where the name is the name of an exported variable and the
value is the variable's current value. For programs started
with a exec(S) call, the environment is available through
the external pointer environ. For other programs,
individual variables in environment are available through
getenv(S) calls.
See Also
csh(C), env(C), exec(S), getenv(S), login(M), profile(M),
sh(C), tz(M)
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