Special shell variables

The shell sets addsuffix, argv, autologout, command, echo_style, edit, gid, group, home, loginsh, oid, path, prompt, prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and version at startup; they do not change thereafter unless changed by the user. The shell updates cwd, dirstack, owd and status when necessary, and sets logout on logout.

The shell synchronizes afsuser, group, home, path, shlvl, term and user with the environment variables of the same names: whenever the environment variable changes the shell changes the corresponding shell variable to match (unless the shell variable is read-only) and vice versa. Note that although cwd and PWD have identical meanings, they are not synchronized in this manner, and that the shell automatically interconverts the different formats of path and PATH.

addsuffix (+)

If set, filename completion adds `/' to the end of directories and a space to the end of normal files when they are matched exactly. Set by default.

afsuser (+)

If set, autologout's autolock feature uses its value instead of the local username for kerberos authentication.

ampm (+)

If set, all times are shown in 12-hour AM/PM format.

argv

The arguments to the shell. Positional parameters are taken from argv, i.e. `$1' is replaced by `$argv[1]', etc. Set by default, but usually empty in interactive shells.

autocorrect (+)

If set, the spell-word editor command is invoked automatically before each completion attempt.

autoexpand (+)

If set, the expand-history editor command is invoked automatically before each completion attempt.

autolist (+)

If set, possibilities are listed after an ambiguous completion. If set to `ambiguous', possibilities are listed only when no new characters are added by completion.

autologout (+)

The first word is the number of minutes of inactivity before automatic logout. The optional second word is the number of minutes of inactivity before automatic locking. When the shell automatically logs out, it prints `auto-logout', sets the variable logout to `automatic' and exits. When the shell automatically locks, the user is required to enter his password to continue working. Five incorrect attempts result in automatic logout. Set to `60' (automatic logout after 60 minutes, and no locking) by default in login and superuser shells, but not if the shell thinks it is running under a window system (i.e. the DISPLAY environment variable is set), the tty is a pseudo-tty (pty) or the shell was not so compiled (see the version shell variable). See also the afsuser and logout shell variables.

backslash_quote (+)

If set, backslashes (`\') always quote `\', `'', and `"'. This may make complex quoting tasks easier, but it can cause syntax errors in csh(1) scripts.

cdpath

A list of directories in which cd should search for subdirectories if they aren't found in the current directory.

command (+)

If set, the command which was passed to the shell with the -c flag (q.v.).

complete (+)

If set to `enhance', completion 1) ignores case and 2) considers periods, hyphens and underscores (`.', `-' and `_') to be word separators and hyphens and underscores to be equivalent.

correct (+)

If set to `cmd', commands are automatically spelling-corrected. If set to `complete', commands are automatically completed. If set to `all', the entire command line is corrected.

cwd

The full pathname of the current directory. See also the dirstack and owd shell variables.

dextract (+)

If set, `pushd +n' extracts the nth directory from the directory stack rather than rotating it to the top.

dirsfile (+)

The default location in which `dirs -S' and `dirs -L' look for a history file. If unset, ~/.cshdirs is used. Because only ~/.tcshrc is normally sourced before ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather than ~/.login.

dirstack (+)

An array of all the directories on the directory stack. `$dirstack[1]' is the current working directory, `$dirstack[2]' the first directory on the stack, etc. Note that the current working directory is `$dirstack[1]' but `=0' in directory stack substitutions, etc. One can change the stack arbitrarily by setting dirstack, but the first element (the current working directory) is always correct. See also the cwd and owd shell variables.

dunique (+)

If set, pushd removes any instances of name from the stack before pushing it onto the stack.

echo

If set, each command with its arguments is echoed just before it is executed. For non-builtin commands all expansions occur before echoing. Builtin commands are echoed before command and filename substitution, since these substitutions are then done selectively. Set by the -x command line option.

echo_style (+)

The style of the echo builtin. May be set to

edit (+)

If set, the command-line editor is used. Set by default in interactive shells.

ellipsis (+)

If set, the `%c'/`%.' and `%C' prompt sequences (see the prompt shell variable) indicate skipped directories with an ellipsis (`...') instead of `/<skipped>'.

fignore (+)

Lists file name suffixes to be ignored by completion.

filec

In tcsh, completion is always used and this variable is ignored. If set in csh, filename completion is used.

gid (+)

The user's real group ID.

group (+)

The user's group name.

histchars

A string value determining the characters used in History substitution (q.v.). The first character of its value is used as the history substitution character, replacing the default character `!'. The second character of its value replaces the character `^' in quick substitutions.

histdup (+)

Controls handling of duplicate entries in the history list. If set to `all' only unique history events are entered in the history list. If set to `prev' and the last history event is the same as the current command, then the current command is not entered in the history. If set to `erase' and the same event is found in the history list, that old event gets erased and the current one gets inserted. Note that the `prev' and `all' options renumber history events so there are no gaps.

histfile (+)

The default location in which `history -S' and `history -L' look for a history file. If unset, ~/.history is used. histfile is useful when sharing the same home directory between different machines, or when saving separate histories on different terminals. Because only ~/.tcshrc is normally sourced before ~/.history, histfile should be set in ~/.tcshrc rather than ~/.login.

histlit (+)

If set, builtin and editor commands and the savehist mechanism use the literal (unexpanded) form of lines in the history list. See also the toggle-literal-history editor command.

history

The first word indicates the number of history events to save. The optional second word (+) indicates the format in which history is printed; if not given, `%h\t%T\t%R\n' is used. The format sequences are described below under prompt; note the variable meaning of `%R'. Set to `100' by default.

home

Initialized to the home directory of the invoker. The filename expansion of `~' refers to this variable.

ignoreeof

If set to the empty string or `0' and the input device is a terminal, the end-of-file command (usually generated by the user by typing `^D' on an empty line) causes the shell to print `Use "exit" to leave tcsh.' instead of exiting. This prevents the shell from accidentally being killed. If set to a number n, the shell ignores n - 1 consecutive end-of-files and exits on the nth. (+) If unset, `1' is used, i.e. the shell exits on a single `^D'.

implicitcd (+)

If set, the shell will treat directory names typed as commands as though they were requests to change to that directory. If set to verbose, the change of directory will be echoed to the standard output. This behavior is inhibited in non-interactive shell scripts, or for command strings with more than one word. Changing directory takes precedence over executing a a like-named command, but it is done after alias substitutions. Tilde and variable expansions work as expected.

inputmode (+)

If set to `insert' or `overwrite', puts the editor into that input mode at the beginning of each line.

listflags (+)

If set to `x', `a' or `A', or any combination thereof (e.g. `xA'), they are used as flags to ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a combination (e.g. `ls -FxA'): `a' shows all files (even if they start with a `.'), `A' shows all files but `.' and `..', and `x' sorts across instead of down. If the second word of listflags is set, it is used as the path to `ls(1)'.

listjobs (+)

If set, all jobs are listed when a job is suspended. If set to `long', the listing is in long format.

listlinks (+)

If set, the ls-F builtin command shows the type of file to which each symbolic link points.

listmax (+)

The maximum number of items which the list-choices editor command will list without asking first.

listmaxrows (+)

The maximum number of rows of items which the list-choices editor command will list without asking first.

loginsh (+)

Set by the shell if it is a login shell. Setting or unsetting it within a shell has no effect. See also shlvl.

logout (+)

Set by the shell to `normal' before a normal logout, `automatic' before an automatic logout, and `hangup' if the shell was killed by a hangup signal (see Signal handling). See also the autologout shell variable.

mail

The names of the files or directories to check for incoming mail, separated by whitespace, and optionally preceeded by a numeric word. Before each prompt, if 10 minutes have passed since the last check, the shell checks each file and says `You have new mail.' (or, if mail contains multiple files, `You have new mail in name.') if the filesize is greater than zero in size and has a modification time greater than its access time.

matchbeep (+)

If set to `never', completion never beeps. If set to `nomatch', it beeps only when there is no match. If set to `ambiguous, it beeps when there are multiple matches. If set to `notunique', it beeps when there is one exact and other longer matches. If unset, `ambiguous' is used.

nobeep (+)

If set, beeping is completely disabled. See also visiblebell.

noclobber

If set, restrictions are placed on output redirection to insure that files are not accidentally destroyed and that `>>' redirections refer to existing files, as described in the Input/output section.

noglob

If set, Filename substitution and Directory stack substitution (q.v.) are inhibited. This is most useful in shell scripts which do not deal with filenames, or after a list of filenames has been obtained and further expansions are not desirable.

nokanji (+)

If set and the shell supports Kanji (see the version shell variable), it is disabled so that the meta key can be used.

nonomatch

If set, a Filename substitution or Directory stack substitution (q.v.) which does not match any existing files is left untouched rather than causing an error. It is still an error for the substitution to be malformed, e.g. `echo [' still gives an error.

nostat (+)

A list of directories (or glob-patterns which match directories; see Filename substitution) that should not be stat(2)ed during a completion operation. This is usually used to exclude directories which take too much time to stat(2), for example /afs.

notify

If set, the shell announces job completions asynchronously. The default is to present job completions just before printing a prompt.

oid (+)

The user's real organization ID. (Domain/OS only)

owd (+)

The old working directory, equivalent to the `-' used by cd and pushd. See also the cwd and dirstack shell variables.

path

A list of directories in which to look for executable commands. A null word specifies the current directory. If there is no path variable then only full path names will execute. path is set by the shell at startup from the PATH environment variable or, if PATH does not exist, to a system-dependent default something like `(/usr/local/bin /usr/bsd /bin /usr/bin .)'. The shell may put `.' first or last in path or omit it entirely depending on how it was compiled; see the version shell variable. A shell which is given neither the -c nor the -t option hashes the contents of the directories in path after reading ~/.tcshrc and each time path is reset. If one adds a new command to a directory in path while the shell is active, one may need to do a rehash for the shell to find it.

printexitvalue (+)

If set and an interactive program exits with a non-zero status, the shell prints `Exit status'.

prompt

The string which is printed before reading each command from the terminal. prompt may include any of the following formatting sequences (+), which are replaced by the given information:

prompt2 (+)

The string with which to prompt in while and foreach loops and after lines ending in `\'. The same format sequences may be used as in prompt (q.v.); note the variable meaning of `%R'. Set by default to `%R? ' in interactive shells.

prompt3 (+)

The string with which to prompt when confirming automatic spelling correction. The same format sequences may be used as in prompt (q.v.); note the variable meaning of `%R'. Set by default to `CORRECT>%R (y|n|e)? ' in interactive shells.

promptchars (+)

If set (to a two-character string), the `%#' formatting sequence in the prompt shell variable is replaced with the first character for normal users and the second character for the superuser.

pushdtohome (+)

If set, pushd without arguments does `pushd ~', like cd.

pushdsilent (+)

If set, pushd and popd do not print the directory stack.

recexact (+)

If set, completion completes on an exact match even if a longer match is possible.

recognize_only_executables (+)

If set, command listing displays only files in the path that are executable. Slow.

rmstar (+)

If set, the user is prompted before `rm *' is executed.

savedirs (+)

If set, the shell does `dirs -S' before exiting.

savehist

If set, the shell does `history -S' before exiting. If the first word is set to a number, at most that many lines are saved. (The number must be less than or equal to history.) If the second word is set to `merge', the history list is merged with the existing history file instead of replacing it (if there is one) and sorted by time stamp and the most recent events are retained. (+)

sched (+)

The format in which the sched builtin command prints scheduled events; if not given, `%h\t%T\t%R\n' is used. The format sequences are described above under prompt; note the variable meaning of `%R'.

shell

The file in which the shell resides. This is used in forking shells to interpret files which have execute bits set, but which are not executable by the system. (See the description of Builtin and non-builtin command execution.) Initialized to the (system-dependent) home of the shell.

shlvl (+)

The number of nested shells. Reset to 1 in login shells. See also loginsh.

status

The status returned by the last command. If it terminated abnormally, then 0200 is added to the status. Builtin commands which fail return exit status `1', all other builtin commands return status `0'.

symlinks (+)

Can be set to several different values to control symbolic link (`symlink') resolution:

tcsh (+)

The version number of the shell in the format `R.VV.PP', where `R' is the major release number, `VV' the current version and `PP' the patchlevel.

term

The terminal type. Usually set in ~/.login as described under Startup and shutdown.

time

If set to a number, then the time builtin (q.v.) executes automatically after each command which takes more than that many CPU seconds. If there is a second word, it is used as a format string for the output of the time builtin. (u) The following sequences may be used in the format string:

tperiod (+)

The period, in minutes, between executions of the periodic special alias.

tty (+)

The name of the tty, or empty if not attached to one.

uid (+)

The user's real user ID.

user

The user's login name.

verbose

If set, causes the words of each command to be printed, after history substitution (if any). Set by the -v command line option.

version (+)

The version ID stamp. It contains the shell's version number (see tcsh), origin, release date, vendor, operating system and machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-separated list of options which were set at compile time. Options which are set by default in the distribution are noted.

visiblebell (+)

If set, a screen flash is used rather than the audible bell. See also nobeep.

watch (+)

A list of user/terminal pairs to watch for logins and logouts. If either the user is `any' all terminals are watched for the given user and vice versa. Setting watch to `(any any)' watches all users and terminals. For example,

who (+)

The format string for watch messages. The following sequences are replaced by the given information:

wordchars (+)

A list of non-alphanumeric characters to be considered part of a word by the forward-word, backward-word etc. editor commands. If unset, `*?_-.[]~=' is used.

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