EXPRESSIONS

Expressions can be given to the C Shell commands like @, exit, if, set, and while. The non-file operators are similar to those in the C programming language and have the same precedence. Null or missing values are considered zero.

File Operators

–d file	true if file is a directory
–e file	true if file exists
–f file	true if file is a regular file
–o file	true if file owned by user
–r file	true if file is readable
–w file	true if file is writable
–x file	true if file is executable
–z file	true if file is zero length

Other Operators

(...)	grouping (used to override precedence)
~	one’s complement
!	logical negation
*, /, %	multiplication, division, modulo
+, –	addition, subtraction
<<, >>	bitwise shift left, bitwise shift right
<, >, <=, >=	less than, greater than, less than or equal to, greater than or equal to
==, !=, =~, !~	equal to, not equal to, equal to pattern, not equal to pattern (used with strings)
&	bitwise AND
^	bitwise exclusive OR
\|	bitwise OR
&&	logical AND
\| \|	logical OR
=	assignment
++, – –	increment, decrement
+=, –=	add assign, subtract assign
*=, /=, %=	multiply assign, divide assign, modulo assign

CONTROL COMMANDS

foreach var (word1 word2 . . . wordn)
                 commands
end

Execute commands once for each word setting var to word. The break and continue commands can be used to terminate or continue the loop early.

goto label

Continue execution after the line with label: (cannot be in a while or for loop).

if (expr) command

Execute a single command if expr returns true

if (expr1) then
         commands1
else if (expr2) then
         commands2
. . .
else
         commands3
endif

Execute commands1 if expr1 returns true, otherwise execute commands2 if expr2 returns true. Execute commands3 if expr1 and expr2 do not return true.

switch (string)
     case label:     commands
                     breaksw
     case label:     commands
                     breaksw
     . . .
     default:        commands
                     breaksw

Execute commands for the case statement whose label matches string. If no case statement matches string, then the commands associated with default are executed. The breaksw commands causes execution to resume after endsw.

while (expr)
         commands
end

Execute commands while expr is true. The break and continue commands can be used to terminate or continue the loop early.

OTHER COMMANDS

:	null command; returns zero exit status
break	exit from current enclosing foreach, or while loop
cd dir	change directory to dir. If dir not specified, change directory to $HOME. If dir is a relative pathname not found in the current directory, cdpath is checked.
chdir [dir]	same as cd
continue	continue at start of next foreach or while loop
dirs	display the current directory list
dirs –l	display the current directory list in long format
echo arguments	display arguments terminated with a newline
echo –n arguments	display arguments without a terminating newline
eval command	evaluate command and execute the result
exec command	replace current process with command
exit	exit from current program with value of status
exit (expr)	exit from current program with value of expr
glob arguments	perform filename expansion on arguments
hashstat	display statistics for hashing attempts
history	display the command history list
history [–hr] n	display n previous commands from history list:
	–h	display without command numbers
	–r	display in reverse order

limit [–h] [resource [ limit ]]	set or display a resource limitation. If –h given (only by the super-user), then hard limits are used instead of the current limits. If no limit is given, then the current limit for resource is displayed. If no resource is given, all current limits are displayed.
	resource can be one of:
	cputime	maximum cpu seconds per process
	filesize	largest single file allowed
	datasize	maximum data size for the process
	stacksize	maximum stack size for the process
	coredumpsize	maximum size of core dump
	limit is a number with an optional scale factor:
	nh	n hours (cputime)
	nk	n kilobytes (all except cputime)
	nm	n megabytes (all except cputime), or n minutes (cputime)
	mm:ss	minutes and seconds (cputime)
login	terminate a login shell, invoke login, and prompt for a user name
login user	terminate a login shell and login as user
login –p	same as login, except preserve current environment
logout	terminate a login shell

nice [priority] [command]	increment/decrement process priority for the current shell or command. The priority can be (default 4):
	+n	increment the process priority value by n
	–n	decrement the process priority value by n (super-user only)
nohup	ignore hangups (HUP) in C shell scripts
nohup command	execute command with hangups (HUP) ignored
onintr	terminate C shell scripts on interrupt
onintr –	ignore all interrupts
onintr label	execute goto label on interrupt
popd	discard top entry from directory stack
popd +n	discard nth entry from directory stack
pushd	switch top two directory stack elements
pushd +n	switch nth directory stack entry and cd to it
pushd dir	move current directory to top of directory stack and cd to dir
rehash	recompute hash table
repeat n command	execute command n times
set	display a list of variable names and their values
shift [var]	shift components of var once to the left, discarding the first component. If no var specified, use argv.
source [–h] file	read and execute commands from file. If –h specified, read commands, but do not execute.
time	display a summary of time used by the current shell
time command	display a summary of time used by command
umask	display current value of the file creation mask
umask mask	set default file creation mask to octal mask
unhash	disable use of internal hash table
unlimit [ resource]	remove limitations from all or the specified resource
unlimit –h [ resource]	remove hard limits from all or the specified resource (super-user only)

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