NAME
csh, %, @, alias, bg, break, breaksw, case, continue,
default, dirs, else, end, endif, endsw, eval, exec, exit,
fg, foreach, glob, goto, hashstat, history, if, jobs, label,
limit, logout, notify, onintr, popd, pushd, rehash, repeat,
set, setenv, shift, source, stop, suspend, switch, then,
umask, unalias, unhash, unlimit, unset, unsetenv, while - C
shell built-in commands, see csh(1)
C-SHELL BUILTIN COMMANDS
Built-in commands are executed within the C shell. If a
built-in command occurs as any component of a pipeline
except the last, it is executed in a subshell.
: Null command. This command is interpreted, but
performs no action.
alias [ name [ def ] ]
Assign def to the alias name. def is a list of
words that may contain escaped history-
substitution metasyntax. name is not allowed to
be alias or unalias. If def is omitted, the alias
name is displayed along with its current defini-
tion. If both name and def are omitted, all
aliases are displayed.
bg [%job] ...
Run the current or specified jobs in the back-
ground.
break Resume execution after the end of the nearest
enclosing foreach or while loop. The remaining
commands on the current line are executed. This
allows multilevel breaks to be written as a list
of break commands, all on one line.
breaksw Break from a switch, resuming after the endsw.
case label:
A label in a switch statement.
cd [ dir ]
chdir [ dir ]
Change the shell's working directory to directory
dir. If no argument is given, change to the home
directory of the user. If dir is a relative path-
name not found in the current directory, check for
it in those directories listed in the cdpath vari-
able. If dir is the name of a shell variable
whose value starts with a /, change to the direc-
tory named by that value.
continue Continue execution of the nearest enclosing while
or foreach.
default: Labels the default case in a switch statement.
The default should come after all case labels.
Any remaining commands on the command line are
first executed.
dirs [ -l ]
Print the directory stack, most recent to the
left; the first directory shown is the current
directory. With the -l argument, produce an unab-
breviated printout; use of the ~ notation is
suppressed.
echo [ -n ] list
The words in list are written to the shell's stan-
dard output, separated by SPACE characters. The
output is terminated with a NEWLINE unless the -n
option is used.
eval argument ...
Reads the arguments as input to the shell, and
executes the resulting command(s). This is usu-
ally used to execute commands generated as the
result of command or variable substitution, since
parsing occurs before these substitutions. See
tset(1) for an example of how to use eval.
exec command
Execute command in place of the current shell,
which terminates.
exit [ (expr) ]
The shell exits, either with the value of the
status variable, or with the value of the speci-
fied by the expression expr.
fg % [ job ]
Bring the current or specified job into the fore-
ground.
foreach var (wordlist)
...
end The variable var is successively set to each
member of wordlist. The sequence of commands
between this command and the matching end is exe-
cuted for each new value of var. (Both foreach
and end must appear alone on separate lines.)
The built-in command continue may be used to con-
tinue the loop prematurely and the built-in
command break to terminate it prematurely. When
this command is read from the terminal, the loop
is read up once prompting with ? before any state-
ments in the loop are executed.
glob wordlist
Perform filename expansion on wordlist. Like
echo, but no \ escapes are recognized. Words are
delimited by null characters in the output.
goto label
The specified label is filename and command
expanded to yield a label. The shell rewinds its
input as much as possible and searches for a line
of the form label: possibly preceded by SPACE or
TAB characters. Execution continues after the
indicated line. It is an error to jump to a label
that occurs between a while or for built-in, and
its corresponding end.
hashstat Print a statistics line indicating how effective
the internal hash table has been at locating com-
mands (and avoiding execs). An exec is attempted
for each component of the path where the hash
function indicates a possible hit, and in each
component that does not begin with a `/'.
history [ -hr ] [ n ]
Display the history list; if n is given, display
only the n most recent events.
-r Reverse the order of printout to be most
recent first rather than oldest first.
-h Display the history list without leading
numbers. This is used to produce files suit-
able for sourcing using the -h option to
source.
if (expr) command
If the specified expression evaluates to true, the
single command with arguments is executed. Vari-
able substitution on command happens early, at the
same time it does for the rest of the if command.
command must be a simple command, not a pipeline,
a command list, or a parenthesized command list.
Note: I/O redirection occurs even if expr is
false, when command is not executed (this is a
bug).
if (expr) then
...
else if (expr2) then
...
else
...
endif If expr is true, commands up to the first else are
executed. Otherwise, if expr2 is true, the com-
mands between the else if and the second else are
executed. Otherwise, commands between the else
and the endif are executed. Any number of else if
pairs are allowed, but only one else. Only one
endif is needed, but it is required. The words
else and endif must be the first nonwhite charac-
ters on a line. The if must appear alone on its
input line or after an else.)
jobs[ -l ]
List the active jobs under job control.
-l List process IDs, in addition to the normal
information.
kill [ -sig ] [ pid ] [ %job ] ...
kill -l Send the TERM (terminate) signal, by default, or
the signal specified, to the specified process ID,
the job indicated, or the current job. Signals
are either given by number or by name. There is
no default. Typing kill does not send a signal to
the current job. If the signal being sent is TERM
(terminate) or HUP (hangup), then the job or pro-
cess is sent a CONT (continue) signal as well.
-l List the signal names that can be sent.
limit [ -h ] [ resource [ max-use ] ]
Limit the consumption by the current process or
any process it spawns, each not to exceed max-use
on the specified resource. If max-use is omitted,
print the current limit; if resource is omitted,
display all limits.
-h Use hard limits instead of the current lim-
its. Hard limits impose a ceiling on the
values of the current limits. Only the
super-user may raise the hard limits.
resource is one of:
cputime Maximum CPU seconds per pro-
cess.
filesize Largest single file allowed.
datasize Maximum data size (including
stack) for the process.
stacksize Maximum stack size for the
process.
coredumpsize Maximum size of a core dump
(file).
descriptors Maximum value for a file
descriptor.
max-use is a number, with an optional scaling fac-
tor, as follows:
nh Hours (for cputime).
nk n kilobytes. This is the
default for all but cputime.
nm n megabytes or minutes (for
cputime).
mm:ss Minutes and seconds (for cpu-
time).
login [ username|-p ]
Terminate a login shell and invoke login(1). The
.logout file is not processed. If username is
omitted, login prompts for the name of a user.
-p Preserve the current environment (variables).
logout Terminate a login shell.
nice [ +n|-n ] [ command ]
Increment the process priority value for the shell
or for command by n. The higher the priority
value, the lower the priority of a process, and
the slower it runs. When given, command is always
run in a subshell, and the restrictions placed on
commands in simple if commands apply. If command
is omitted, nice increments the value for the
current shell. If no increment is specified, nice
sets the nice value to 4. The range of nice
values is from -20 through 19. Values of n out-
side this range set the value to the lower, or to
the higher boundary, respectively.
+n Increment the process priority value by
n.
-n Decrement by n. This argument can be
used only by the super-user.
nohup [ command ]
Run command with HUPs ignored. With no arguments,
ignore HUPs throughout the remainder of a script.
When given, command is always run in a subshell,
and the restrictions placed on commands in simple
if commands apply. All processes detached with &
are effectively nohup'd.
notify [ %job ] ...
Notify the user asynchronously when the status of
the current, or of specified jobs, changes.
onintr [ - | label]
Control the action of the shell on interrupts.
With no arguments, onintr restores the default
action of the shell on interrupts. (The shell
terminates shell scripts and returns to the termi-
nal command input level). With the - argument,
the shell ignores all interrupts. With a label
argument, the shell executes a goto label when an
interrupt is received or a child process ter-
minates because it was interrupted.
popd [+n]
Pop the directory stack, and cds to the new top
directory. The elements of the directory stack
are numbered from 0 starting at the top.
+n Discard the n'th entry in the stack.
pushd [+n | dir]
Push a directory onto the directory stack. With
no arguments, exchange the top two elements.
+n Rotate the n'th entry to the top of the stack
and cd to it.
dir Push the current working directory onto the
stack and change to dir.
rehash Recompute the internal hash table of the contents
of directories listed in the path variable to
account for new commands added.
repeat count command
Repeat command count times command is subject to
the same restrictions as with the one-line if
statement.
set [var [ = value ] ]
set var[n] = word
With no arguments, set displays the values of all
shell variables. Multiword values are displayed
as a parenthesized list. With the var argument
alone, set assigns an empty (null) value to the
variable var. With arguments of the form var =
value set assigns value to var, where value is one
of:
word A single word (or quoted string).
(wordlist) A space-separated list of words
enclosed in parentheses.
Values are command and filename expanded before
being assigned. The form set var[n] = word
replaces the n'th word in a multiword value with
word.
setenv [ VAR [ word ] ]
With no arguments, setenv displays all environment
variables. With the VAR argument sets the
environment variable VAR to have an empty (null)
value. (By convention, environment variables are
normally given upper-case names.) With both VAR
and word arguments setenv sets the environment
variable NAME to the value word, which must be
either a single word or a quoted string. The most
commonly used environment variables, USER, TERM,
and PATH, are automatically imported to and
exported from the csh variables user, term, and
path; there is no need to use setenv for these.
In addition, the shell sets the PWD environment
variable from the csh variable cwd whenever the
latter changes.
shift [ variable ]
The components of argv, or variable, if supplied,
are shifted to the left, discarding the first com-
ponent. It is an error for the variable not to be
set, or to have a null value.
source [ -h ] name
Reads commands from name. source commands may be
nested, but if they are nested too deeply the
shell may run out of file descriptors. An error
in a sourced file at any level terminates all
nested source commands.
-h Place commands from the file name on the
history list without executing them.
stop [%job] ...
Stop the current or specified background job.
suspend Stop the shell in its tracks, much as if it had
been sent a stop signal with ^Z. This is most
often used to stop shells started by su.
switch (string)
case label:
...
breaksw
...
default:
...
breaksw
endsw Each label is successively matched, against the
specified string, which is first command and
filename expanded. The file metacharacters *, ?
and [...] may be used in the case labels, which
are variable expanded. If none of the labels
match before a "default" label is found, execution
begins after the default label. Each case state-
ment and the default statement must appear at the
beginning of a line. The command breaksw contin-
ues execution after the endsw. Otherwise control
falls through subsequent case and default state-
ments as with C. If no label matches and there is
no default, execution continues after the endsw.
time [ command ]
With no argument, print a summary of time used by
this C shell and its children. With an optional
command, execute command and print a summary of
the time it uses.
umask [ value ]
Display the file creation mask. With value set
the file creation mask. value is given in octal,
and is XORed with the permissions of 666 for files
and 777 for directories to arrive at the permis-
sions for new files. Common values include 002,
giving complete access to the group, and read (and
directory search) access to others, or 022, giving
read (and directory search) but not write permis-
sion to the group and others.
unalias pattern
Discard aliases that match (filename substitution)
pattern. All aliases are removed by unalias *.
unhash Disable the internal hash table.
unlimit [ -h ] [ resource ]
Remove a limitation on resource. If no resource
is specified, then all resource limitations are
removed. See the description of the limit command
for the list of resource names.
-h Remove corresponding hard limits. Only
the super-user may do this.
unset pattern
Remove variables whose names match (filename sub-
stitution) pattern. All variables are removed by
`unset *'; this has noticeably distasteful side-
effects.
unsetenv variable
Remove variable from the environment. Pattern
matching, as with unset is not performed.
wait Wait for background jobs to finish (or for an
interrupt) before prompting.
while (expr)
...
end While expr is true (evaluates to non-zero), repeat
commands between the while and the matching end
statement. break and continue may be used to ter-
minate or continue the loop prematurely. The
while and end must appear alone on their input
lines. If the shell's input is a terminal, it
prompts for commands with a question-mark until
the end command is entered and then performs the
commands in the loop.
%[ job ] [ & ]
Bring the current or indicated job to the fore-
ground. With the ampersand, continue running job
in the background.
@ [ var =expr ]
@ [ var[n] =expr ]
With no arguments, display the values for all
shell variables. With arguments, the variable
var, or the n'th word in the value of var, to the
value that expr evaluates to. (If [n] is sup-
plied, both var and its n'th component must
already exist.)
If the expression contains the characters >, <, &
or |, then at least this part of expr must be
placed within parentheses.
The operators *=, +=, etc., are available as in C.
The space separating the name from the assignment
operator is optional. Spaces are, however, manda-
tory in separating components of expr that would
otherwise be single words.
Special postfix operators, ++ and -- increment or
decrement name, respectively.
SEE ALSO
csh(1), sh(1)