csh(1)

Read commands from the (single) following argument which must be present. Any remaining arguments are placed in argv.

C shell exits if any invoked command terminates abnormally or yields a non-zero exit status.

Suppress execution of the .cshrc file in your home directory, thus speeding up shell start-up time.

Force csh to respond interactively when called from a device other than a computer terminal (such as another computer). csh normally responds non-interactively. If csh is called from a computer terminal, it always responds interactively, regardless of which options are selected.

Parse but do not execute commands. This is useful for checking syntax in shell scripts. All substitutions are performed (history, command, alias, etc.).

Take command input from the standard input.

Read and execute a single line of input.

Set the verbose shell variable, causing command input to be echoed to the standard output device after history substitutions are made.

Set the echo shell variable, causing all commands to be echoed to the standard error immediately before execution.

Disable the tenex features which use the ESC key for command/file name completion and CTRL-D for listing available files (see the CSH UTILITIES section below)

Set the verbose variable before .cshrc is executed so that all .cshrc commands are also echoed to the standard output.

Set the echo variable before .cshrc is executed so that all .cshrc commands are also echoed to the standard output.

The first form prints all aliases. The second form prints the alias for name. The third form assigns the specified wordlist as the alias of name. Command and file name substitution are performed on wordlist. name cannot be alias or unalias.

Put the current (job not specified) or specified jobs into the background, continuing them if they were stopped.

Causes execution to resume after the end of the nearest enclosing foreach or while. The remaining commands on the current line are executed. Multi-level breaks are thus possible by writing them all on one line.

Causes a break from a switch, resuming after the endsw.

A label in a switch statement as discussed below.

Change the shell's current working directory to directory_name. If not specified, directory_name defaults to your home directory.

If directory_name is not found as a subdirectory of the current working directory (and does not begin with /, ./, or ../), each component of the variable cdpath is checked to see if it has a subdirectory directory_name. Finally, if all else fails, csh treats directory_name as a shell variable. If its value begins with /, this is tried to see if it is a directory. See also cd(1).

Continue execution of the nearest enclosing while or foreach. The rest of the commands on the current line are executed.

Labels the default case in a switch statement. The default should come after all other case labels.

Prints the directory stack; the top of the stack is at the left; the first directory in the stack is the current directory.

The specified words are written to the shell's standard output, separated by spaces, and terminated with a new-line unless the -n option is specified. See also echo(1).

See the descriptions of the foreach, if, switch, and while statements below.

(Same behavior as sh(1).) arguments are read as input to the shell and the resulting command(s) executed. This is usually used to execute commands generated as the result of command or variable substitution, since parsing occurs before these substitutions.

The specified command is executed in place of the current shell.

csh exits either with the value of the status variable (first form) or with the value of the specified expression (second form).

Brings the current (job not specified) or specified jobs into the foreground, continuing them if they were stopped.

The variable name is successively set to each member of wordlist and the sequence of commands between this command and the matching end are executed. (Both foreach and end must appear alone on separate lines.)

The built-in command continue can be used to continue the loop prematurely; the built-in command break to terminate it prematurely. When this command is read from the terminal, the loop is read once, prompting with ? before any statements in the loop are executed. If you make a mistake while typing in a loop at the terminal, use the erase or line-kill character as appropriate to recover.

Like echo but no \ escapes are recognized and words are delimited by null characters in the output. Useful in programs that use the shell to perform file name expansion on a list of words.

The specified word is file name and command expanded to yield a string of the form label. The shell rewinds its input as much as possible and searches for a line of the form label: possibly preceded by blanks or tabs. Execution continues after the specified line.

Print a statistics line indicating how effective the internal hash table has been at locating commands (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 /.

Displays the history event list. If n is given, only the n most recent events are printed. The -r option reverses the order of printout to be most recent first rather than oldest first. The -h option prints the history list without leading numbers for producing files suitable for the source command.

If expression evaluates true, the single command with arguments is executed. Variable 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, a parenthesized command list, or an aliased command. Input/output redirection occurs even if expression is false, meaning that command is not executed (this is a bug).

If expression1 is true, all commands down to the first else are executed; otherwise if expression2 is true, all commands from the first else down to the second else are executed, etc. Any number of else-if pairs are possible, but only one endif is needed. The else part is likewise optional. (The words else and endif must appear at the beginning of input lines. The if must appear alone on its input line or after an else.)

Lists active jobs. The -l option lists process IDs in addition to the usual information.

Sends either the TERM (terminate) signal or the specified signal to the specified jobs or processes. Signals are either given by number or by names (as given in /usr/include/signal.h, stripped of the SIG prefix (see signal(2)). The signal names are listed by kill -l. There is no default, so kill used alone does not send a signal to the current job. If the signal being sent is TERM (terminate) or HUP (hangup), the job or process is sent a CONT (continue) signal as well. See also kill(1).

Limits the usage by the current process and each process it creates not to (individually) exceed maximum_use on the specified resource. If maximum_use is not specified, then the current limit is displayed; if resource is not specified, then all limitations are given.

If the -h flag is specified, the hard limits are used instead of the current limits. The hard limits impose a ceiling on the values of the current limits. Only the superuser can raise the hard limits, but a user can lower or raise the current limits within the legal range.

Controllable resources currently include:

The maximum_use argument can be specified as a floating-point or integer number followed by a scale factor: k or kilobytes (1024 bytes), m or megabytes, or b or blocks (the units used by the ulimit system call). For both resource names and scale factors, unambiguous prefixes of the names can be used. filesize can be lowered by an instance of csh, but can only be raised by an instance whose effective user ID is root. For more information, refer to the documentation for the ulimit system call.

Terminates a login shell, replacing it with an instance of /usr/bin/login. This is one way to log off, included for compatibility with sh(1).

Terminates a login shell. Especially useful if ignoreeof is set. A similar function, bye, which works for sessions that are not login shells, is provided for historical reasons. Its use is not recommended because it is not part of the standard BSD csh and may not be supported in future releases.

Changes the group identification of the caller; for details see newgrp(1). A new shell is executed by newgrp so that the current shell environment is lost.

The first form sets the nice (run command priority) for this shell to 4 (the default). The second form sets the priority to the given number. The final two forms run command at priority 4 and number respectively. The user with appropriate privileges can raise the priority by specifying negative niceness using nice -number ... command is always executed in a sub-shell, and restrictions placed on commands in simple if statements apply. See also nice(1).

Without an argument, nohup can be used in shell scripts to cause hangups to be ignored for the remainder of the script. With an argument, causes the specified command to be run with hangups ignored. All processes executed in the background with & are effectively nohuped as described under Jobs in the COMMANDS section.

Causes the shell to notify the user asynchronously when the status of the current (job not specified) or specified jobs changes; normally notification is presented before a prompt. This is automatic if the shell variable notify is set.

Controls the action of the shell on interrupts. With no arguments, onintr restores the default action of the shell on interrupts, which action is to terminate shell scripts or return to the terminal command input level. If - is specified, all interrupts are ignored. If a label is given, the shell executes a goto label when an interrupt is received or a child process terminates because it was interrupted.

If the shell is running in the background and interrupts are being ignored, onintr has no effect; interrupts continue to be ignored by the shell and all invoked commands.

Pops the directory stack, returning to the new top directory. With an argument, discards the nth entry in the stack. The elements of the directory stack are numbered from 0 starting at the top. A synonym for popd, called rd, is provided for historical reasons. Its use is not recommended because it is not part of the standard BSD csh and may not be supported in future releases.

With no arguments, pushd exchanges the top two elements of the directory stack. Given a name argument, pushd changes to the new directory (using cd) and pushes the old current working directory (as in csw) onto the directory stack. With a numeric argument, pushd rotates the nth argument of the directory stack around to be the top element and changes to that directory. The members of the directory stack are numbered from the top starting at 0. A synonym for pushd, called gd, is provided for historical reasons. Its use is not recommended since it is not part of the standard BSD csh and may not be supported in future releases.

Causes the internal hash table of the contents of the directories in the path variable to be recomputed. This is needed if new commands are added to directories in the path while you are logged in. This should only be necessary if you add commands to one of your own directories or if a systems programmer changes the contents of one of the system directories.

The specified command (which is subject to the same restrictions as the command in the one-line if statement above) is executed count times. I/O redirections occur exactly once, even if count is 0.

The first form of set shows the value of all shell variables. Variables whose value is other than a single word print as a parenthesized word list. The second form sets name to the null string. The third form sets name to the single word. The fourth form sets the indexth component of name to word; this component must already exist. The final form sets name to the list of words in wordlist. In all cases the value is command and file-name expanded.

These arguments can be repeated to set multiple values in a single set command. Note, however, that variable expansion happens for all arguments before any setting occurs.

Sets the value of environment variable name to be value, a single 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.

If no argument is given, the members of argv are shifted to the left, discarding argv[1]. An error occurs if argv is not set or has less than two strings assigned to it. When variable is specified, shift performs the same function on the specified variable.

csh reads commands from name. source commands can be nested, but if nested too deeply the shell may run out of file descriptors or reach the max stack size (see maxssiz(5)). An error in a source at any level terminates all nested source commands. Normally, input during source commands is not placed on the history list. The -h option can be used to place commands in the history list without being executing them.

Stops the current (no argument) or specified jobs executing in the background.

Causes csh to stop as if it had been sent a suspend signal. Since csh normally ignores suspend signals, this is the only way to suspend the shell. This command gives an error message if attempted from a login shell.

Each case label (str1) is successively matched against the specified string which is first command and file name expanded. The form of the case labels is the Pattern Matching Notation with the exception that non-matching lists in bracket expressions are not supported (see regexp(5)). If none of the labels match before a default label is found, the execution begins after the default label. Each case label and the default label must appear at the beginning of a line. The breaksw command causes execution to continue after the endsw. Otherwise, control may fall through case labels and default labels as in C. If no label matches and there is no default, execution continues after the endsw.

When command is not specified, a summary of time used by this shell and its children is printed. If specified, the simple command is timed and a time summary as described under the time variable is printed. If necessary, an extra shell is created to print the time statistic when the command completes.

The current file creation mask is displayed (value not specified) or set to the specified value. The mask is given in octal. Common values for the mask are 002, which gives all permissions to the owner and group and read and execute permissions to all others, or 022, which gives all permissions to the owner, and only read and execute permission to the group and all others. See also umask(1).

All aliases whose names match the specified pattern are discarded. Thus, all aliases are removed by unalias *. No error occurs if pattern does not match an existing alias.

Use of the internal hash table to speed location of executed programs is disabled.

All variables whose names match the specified pattern are removed. Thus, all variables are removed by unset *; this has noticeably undesirable side-effects. No error occurs if pattern matches nothing.

Removes all variables whose names match the specified pattern from the environment. See also the setenv command above and printenv(1).

Waits for all background jobs to terminate. If the shell is interactive, an interrupt can disrupt the wait, at which time the shell prints names and job numbers of all jobs known to be outstanding.

While the specified expression evaluates non-zero, the commands between the while and the matching end are evaluated. break and continue can be used to terminate or continue the loop prematurely. (The while and end must appear alone on their input lines.) If the input is a terminal (i.e., not a script), prompting occurs the first time through the loop as for the foreach statement.

Brings the specified job into the foreground.

Continues the specified job in the background.

The first form prints the values of all the shell variables. The second form sets the specified name to the value of expression. If the expression contains <, >, &, or |, at least this part of the expression must be placed within parentheses. The third form assigns the value of expression to the indexth argument of name. Both name and its indexth component must already exist.

The operators *=, +=, etc., are available as in C. White space can optionally separate the name from the assignment operator. However, spaces are mandatory in separating components of expression which would otherwise be single words.

Special postfix ++ and -- operators increment and decrement name, respectively (e.g., @ i++).

First word (i.e., the command name itself).

nth word.

First argument. (This is equivalent to 1.)

Last word.

Range of words from a through b. Special cases are -y, an abbreviation for "word 0 through word y "; and x-, which means "word x up to, but not including, word $ ".

Range from the second word through the last word.

Used with a search sequence to substitute the immediately preceding matching word.

Use only the first component of a path name by removing all following components.

Use the root file name by removing any trailing suffix (.xxx).

Use the file name's trailing suffix (.xxx) by removing the root name.

substitute the value of r for the value l in the indicated command.

Use only the final file name of a path name by removing all leading path name components.

Repeat the previous substitution.

Print the new command but do not execute it.

Quote the substituted words, preventing further substitutions.

Like q, but break into words at blanks, tabs and newlines.

Use a global command as a prefix to another modifier to cause the specified change to be made globally. All words in the command are changed, one change per word, and each string enclosed in single quotes (') or double quotes (") is treated as a single word.

read access

write access

execute access

existence

ownership

zero size

plain file

directory

ampersand;

vertical bar;

semicolon;

less-than sign;

greater-than sign;

left parenthesis;

right parenthesis;

double ampersand;

double vertical bar;

double less-than sign;

double greater-than sign;

comment delimiter

When interpreted, this sequence is replaced by the words of the value of the variable variable_name, each separated by a blank. Braces insulate variable_name from subsequent characters that would otherwise be interpreted to be part of the variable name itself.

If variable_name is not a csh variable, but is set in the environment, that value is used. Non-csh variables cannot be modified as shown below.

This modification selects only some of the words from the value of variable_name. The selector is subjected to variable substitution, and can consist of a single number or two numbers separated by a dash. The first word of a variable's value is numbered 1. If the first number of a range is omitted it defaults to 1. If the last member of a range is omitted it defaults to the total number of words in the variable ($#variable_name). An asterisk metacharacter used as a selector selects all words.

This form gives the number of words in the variable, and is useful for forms using a [selector] option.

This form substitutes the name of the file from which command input is being read. An error occurs if the file name is not known.

This form is equivalent to an indexed selection from the variable argv ($argv[number]).

This is equivalent to selecting all of argv ($argv[*]).

Substitutes the string 1 if variable_name is set, 0 if it is not.

Substitutes 1 if the current input file name is known, 0 if it is not.

Substitutes the (decimal) process number of the (parent) shell.

Substitutes a line from the standard input, with no further interpretation thereafter. It can be used to read from the keyboard in a shell script.

This variable is set to the arguments of the csh command statement. It is from this variable that positional parameters are substituted; i.e., $1 is replaced by $argv[1], etc.

This variable gives a list of alternate directories searched to find subdirectories in chdir commands.

This variable contains the absolute path name of the current working directory. Whenever changing directories (using cd), this variable is updated.

This variable is set by the -x command line option. If set, all built-in commands and their arguments are echoed to the standard output device just before being executed. Built-in commands are echoed before command and file name substitution, since these substitutions are then done selectively. For non-built-in commands, all expansions occur before echoing.

This variable is used to create the command history buffer and to set its size. If this variable is not set, no command history is maintained and history substitutions cannot be made. Very large values of history can cause shell memory overflow. Values of 10 or 20 are normal. All commands, executable or not, are saved in the command history buffer.

This variable contains the absolute path name to your home directory. The variable home is initialized from the HP-UX environment. File name expansion of tilde (~) refers to this variable.

If set, csh ignores end-of-file characters from input devices that are terminals. csh exits normally when it encounters the end-of-file condition (CTRL-D typed as the first character on a command line). Setting ignoreeof prevents the current shell from being killed by an accidental (CTRL-D. However, to prevent an infinite loop of EOF input, csh terminates if it receives 26 consecutive EOFs.

This variable contains a list of the files where csh checks for your mail. csh periodically (default is 10 minutes) checks this variable before producing a prompt upon command completion. If the variable contains a file name that has been modified since the last check (resulting from mail being put in the file), csh prints You have new mail.

If the first word of the value of mail is numeric, that number specifies a different mail checking interval in seconds.

If multiple mail files are specified, the shell says New mail in file_name, where file_name is the file containing the mail.

This variable places restrictions on output redirection to ensure that regular files are not accidentally destroyed, and that commands using append redirection (>>) refer to existing files.

If set, file name expansion is inhibited. This is most useful in shell scripts that are not dealing with file names, or after a list of file names has been obtained and further expansions are not desirable.

If set, it is no longer an error for a file name expansion to not match any existing files. If there is no match, the primitive pattern is returned. It is still an error for the primitive pattern to be malformed. For example, 'echo [' still gives an error.

If set, csh notifies you immediately (through your standard output device) of background job completions. The default is unset (indicate job completions just before printing a prompt).

Each word of the path variable specifies a directory in which commands are to be sought for execution. A null word specifies your current working directory. If there is no path variable, only full path names can be executed. When path is not set and when users do not specify full path names, csh searches for the command through the directories . (current directory) and /usr/bin. A csh which is given neither the -c nor the -t option normally hashes the contents of the directories in the path variable after reading .cshrc, and each time the path variable is reset. If new commands are added to these directories while the shell is active, it is necessary to execute rehash for csh to access these new commands.

This variable lets you select your own prompt character string. The prompt is printed before each command is read from an interactive terminal input. If a ! appears in the string, it is replaced by the current command history buffer event number unless a preceding \ is given. The default prompt is the percent sign (%) for users and the # character for the super-user.

The number of lines from the history list that are saved in ~/.history when the user logs out. Large values for savehist slow down the csh during startup.

This variable contains the name of the file in which the csh program resides. This variable is used in forking shells to interpret files that have their execute bits set but which are not executable by the system. (See the description of Non-Built-In Command Execution).

This variable contains the status value returned by the last command. If the command terminated abnormally, 0200 is added to the status variable's value. Built-in commands which terminated abnormally return exit status 1, and all other built-in commands set status to 0.

This variable contains a numeric value that controls the automatic timing of commands. If set, csh prints, for any command taking more than the specified number of cpu seconds, a line of information to the standard output device giving user, system, and real execution times plus a utilization percentage. The utilization percentage is the ratio of user plus system times to real time. This message is printed after the command finishes execution.

This variable is set by the -v command line option. If set, the words of each command are printed on the standard output device after history substitutions have been made.

Open file name (which is first variable, command and file name expanded) as the standard input.

Read the shell input up to a line which is identical to word. word is not subjected to variable, file name or command substitution, and each input line is compared to word before any substitutions are done on this input line. Unless a quoting \, ", ', or ` appears in word, variable and command substitution is performed on the intervening lines, allowing \ to quote $, \ and `. Commands which are substituted have all blanks, tabs, and newlines preserved, except for the final newline which is dropped. The resultant text is placed in an anonymous temporary file which is given to the command as standard input.

The file name is used as standard output. If the file does not exist, it is created; if the file exists, it is truncated, and its previous contents are lost.

If the variable noclobber is set, the file must not exist or be a character special file (e.g., a terminal or /dev/null) or an error results. This helps prevent accidental destruction of files. In this case the exclamation point (!) forms can be used to suppress this check.

Note that the noclobber test is only applied to regular files, not to named pipes or other file types.

The forms involving the ampersand character (&) route the standard error into the specified file as well as the standard output. name is expanded in the same way as < input file names are.

Uses file name as standard output the same as >, but appends output to the end of the file. If the variable noclobber is set, it is an error for the file not to exist unless one of the ! forms is given. Otherwise, it is similar to >.