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This is a list of some of the most commonly used variables.
For more information, see the man pages for the shell that
you are using.
Some terms used in this listing, such as wildcards, aliases,
redirection, and jobs, are discussed in the section on
UNIX shells.
-
cdpath
-
When you change to another directory, if it is not a full
path name starting with /, the shell checks to see if the
directory exists within the current directory, if it fails
to find it there, it then checks the cdpath variable for a
list of directories to search for the directory name, and
if found changes directory to that directory.
-
cwd
-
The shell sets this to the full path name of the current
directory when you change your directory. If you change
directory through a link, that path name is relative to the
link. That is, it is not the actual path, but the path you
followed though the link.
-
echo
-
If this variable exists, the shell will echo the command
and all arguments before executing the command. It echoes
back the command and arguments in its final form, after
variable, wild card, and alias expansion.
-
history
-
Sets the number of previously executed commands to
remember. After the execution of every command, the command
with its arguments in put on a list, after the list has
reached the set number of commands, the older ones are
discarded.
-
home
-
Set by the shell upon login, the home variable contains the
full path name to your home directory. If changed, both the
cd command and ~ will refer to the new path.
-
ignoreeof
-
If set, the shell will not exit when a ^D (control-D, or
end of file) is encountered on the command line. Since ^D
is used as an end of file, typing ^D in the shell normally
exits the shell.
-
mail
-
The shell can be told to tell you when and where (which
file) you have received mail. If set, the shell checks by
default every ten minutes to see if you have mail, and if
you do it will follow the last command's output with "You
have new mail". To change the interval in seconds at which
the shell checks the mail file, use a numeric value as the
first (or only) argument when setting the mail variable. If
you need to change the mail file that the shell looks at
(generally, it will look at the default file mail is
delivered to), or add another mail file for it to watch,
specify it after the time interval or by itself when
setting mail. Examples: To have the shell check mail every
minute type set mail=60, to have the shell check the file
joebob.mbox in your home directory, type set
mail=joebob.mbox, and finally if you want to have it do
both and check /var/spool/mail too, type set mail=(60
joebob.mbox /var/spool/mail). In the later example, when
mail arrives the shell will report which file the new mail
arrived in.
-
noclobber
-
If set, noclobber prevents files from being overwritten on
redirection of output.
-
noglob
-
If set, noglob prevents wild card characters from being
expanded.
-
nonomatch
-
If set, the shell will not complain if no files match a
wild card expression. Normally, if no files match the
expression, the shell will not execute the command, in the
case of nonomatch, the command will be executed and given
the wild card as the argument if it can't find matching
files.
-
notify
-
If set, the shell will notify you exactly when a job
completes, rather than displaying it before printing a
prompt.
-
path
-
This is a list of directories the shell will search when it
starts up. The shell will compile a list, called a hash
table, of all the executable files found in the directories
listed in the path variable. When you issue a command, the
shell searches the table for the command, unless the
command issued contain a path name (i.e. bin/command or
/usr/local/bin/command). When the shell checks for the
executable, it looks at the list in order that the entries
were added, so if commands with the same name are
encountered, the one found in the directory first in the
path will be the one it executes.
-
prompt
-
Sets the string you see when the shell is ready for input.
If you put a '!' in the string, the shell will replace it
with the current numerical history number. Note: since this
is a string value, you need to quote the whole string.
-
savehist
-
The number of previously executed commands to save in
~/.history when you exit the shell. This file is normally
loaded when you start a new shell.
-
verbose
-
Causes commands to be echoed before execution, this is done
after any history substitution of the command, (i.e. !!
would print out the last command typed in, then it would be
executed.
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