csh.1

早期freebsd实现

.Ar command
with arguments is executed.
Variable substitution on
.Ar command
happens early, at the same
time it does for the rest of the
.Ic if
command.
.Ar Command
must be a simple command, not
a pipeline, a command list, or a parenthesized command list.
Input/output redirection occurs even if
.Ar expr
is false, i.e., when command is
.Sy not
executed (this is a bug).
.Pp
.It Ic if ( Ar expr ) Ic then
.It ...
.It Ic else if ( Ar expr2 ) Ic then
.It ...
.It Ic else
.It ...
.It Ic endif
If the specified
.Ar expr
is true then the commands up to the first
.Ic else
are executed; otherwise if
.Ar expr2
is true then the commands up to the
second
.Ic else
are executed, etc.
Any number of
.Ic else-if
pairs are possible; only one
.Ic endif
is needed.
The
.Ic else
part is likewise optional.
(The words
.Ic else
and
.Ic endif
must appear at the beginning of input lines;
the
.Ic if
must appear alone on its input line or after an
.Ic else . )
.Pp
.It Ic jobs
.It Ic jobs Fl l
Lists the active jobs; the
.Fl l
option lists process id's in addition to the normal information.
.Pp
.It Ic kill % Ns Ar job
.It Ic kill Ar pid
.It Ic kill Fl sig Ar pid ...
.It Ic kill Fl l
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
.Pa /usr/include/signal.h,
stripped of the prefix ``SIG'').
The signal names are listed by ``kill \-l''.
There is no default, just saying `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 process will be sent a CONT (continue) signal as well.
.Pp
.It Ic limit
.It Ic limit Ar resource
.It Ic limit Ar resource maximum-use
.It Ic limit Fl h
.It Ic limit Fl h Ar resource
.It Ic limit Fl h Ar resource maximum-use
Limits the consumption by the current process and each process
it creates to not individually exceed
.Ar maximum-use
on the
specified
.Ar resource  .
If no
.Ar maximum-use
is given, then
the current limit is printed; if no
.Ar resource
is given, then
all limitations are given.  If the
.Fl h
flag is given, 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 super-user may raise the hard limits,
but a user may lower or raise the current limits within the legal range.
.Pp
Resources controllable currently include
.Ar cputime
(the maximum
number of cpu-seconds to be used by each process),
.Ar filesize
(the largest single file that can be created),
.Ar datasize
(the maximum growth of the data+stack region via
.Xr sbrk  2
beyond the end of the program text),
.Ar stacksize
(the maximum
size of the automatically-extended stack region), and
.Ar coredumpsize
(the size of the largest core dump that will be created).
.Pp
The
.Ar maximum-use
may be given as a (floating point or integer)
number followed by a scale factor.  For all limits other than
.Ar cputime
the default scale is `k' or `kilobytes' (1024 bytes);
a scale factor of `m' or `megabytes' may also be used.
For
.Ar cputime
the default scale is `seconds';
a scale factor of `m' for minutes
or `h' for hours, or a time of the form `mm:ss' giving minutes
and seconds also may be used.
.Pp
For both
.Ar resource
names and scale factors, unambiguous prefixes
of the names suffice.
.Pp
.It Ic login
Terminate a login shell, replacing it with an instance of
.Pa /bin/login.
This is one way to log off, included for compatibility with
.Xr sh  1  .
.Pp
.It Ic logout
Terminate a login shell.
Especially useful if
.Ic ignoreeof
is set.
.Pp
.It Ic nice
.It Ic nice Ar +number
.It Ic nice Ar command
.It Ic nice Ar +number command
The first form sets the
scheduling priority
for this shell to 4.
The second form sets the
priority
to the given
.Ar number .
The final two forms run command at priority 4 and
.Ar number
respectively.
The greater the number, the less cpu the process will get.
The super-user may specify negative priority by using `nice \-number ...'.
.Ar Command
is always executed in a sub-shell, and the restrictions
placed on commands in simple
.Ic if
statements apply.
.Pp
.It Ic nohup
.It Ic nohup Ar command
The first form can be used in shell scripts to cause hangups to be
ignored for the remainder of the script.
The second form causes the specified command to be run with hangups
ignored.
All processes detached with `&' are effectively
.Ic nohup Ns \'ed .
.Pp
.It Ic notify
.It Ic notify % Ns Ar job ...
Causes the shell to notify the user asynchronously when the status of the
current or specified jobs change; normally notification is presented
before a prompt.  This is automatic if the shell variable
.Ic notify
is set.
.Pp
.It Ic onintr
.It Ic onintr Fl
.It Ic onintr Ar label
Control the action of the shell on interrupts.
The first form restores the default action of the shell on interrupts
which is to terminate shell scripts or to return to the terminal command
input level.
The second form `onintr \-' causes all interrupts to be ignored.
The final form causes the shell to execute a `goto label' when
an interrupt is received or a child process terminates because
it was interrupted.
.Pp
In any case, if the shell is running detached and interrupts are
being ignored, all forms of
.Ic onintr
have no meaning and interrupts
continue to be ignored by the shell and all invoked commands.
Finally
.Ic onintr 
statements are ignored in the system startup files where interrupts
are disabled (/etc/csh.cshrc, /etc/csh.login).
.Pp
.It Ic popd
.It Ic popd Ar +n
Pops the directory stack, returning to the new top directory.
With an argument
.Ns \`+ Ar n Ns \'
discards the
.Ar n Ns \'th
entry in the stack.
The members of the directory stack are numbered from the top starting at 0.
.Pp
.It Ic pushd
.It Ic pushd Ar name
.It Ic pushd Ar n
With no arguments,
.Ic pushd
exchanges the top two elements of the directory stack.
Given a
.Ar name
argument,
.Ic pushd
changes to the new directory (ala
.Ic cd )
and pushes the old current working directory
(as in
.Ic csw )
onto the directory stack.
With a numeric argument,
.Ic pushd
rotates the
.Ar n Ns \'th
argument of the directory
stack around to be the top element and changes to it.  The members
of the directory stack are numbered from the top starting at 0.
.Pp
.It Ic rehash
Causes the internal hash table of the contents of the directories in
the
.Ic path
variable to be recomputed.  This is needed if new commands are added
to directories in the
.Ic 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 a system directory.
.Pp
.It Ic repeat Ar count command
The specified
.Ar command
which is subject to the same restrictions
as the
.Ar command
in the one line
.Ic if
statement above,
is executed
.Ar count
times.
I/O redirections occur exactly once, even if
.Ar count
is 0.
.Pp
.It Ic set
.It Ic set Ar name
.It Ic set Ar name Ns =word
.It Ic set Ar name[index] Ns =word
.It Ic set Ar name Ns =(wordlist)
The first form of the command shows the value of all shell variables.
Variables that have other than a single word as their
value print as a parenthesized word list.
The second form sets
.Ar name
to the null string.
The third form sets
.Ar name
to the single
.Ar word .
The fourth form sets
the
.Ar index Ns 'th
component of
.Ar name
to
.Ar word ;
this component must already exist.
The final form sets
.Ar name
to the list of words in
.Ar wordlist .
The value is always command and filename expanded.
.Pp
These arguments may be repeated to set multiple values in a single set command.
Note however, that variable expansion happens for all arguments before any
setting occurs.
.Pp
.It Ic setenv
.It Ic setenv Ar name
.It Ic setenv Ar name value
The first form lists all current environment variables.
It is equivalent to
.Xr printenv 1 .
The last form sets the value of environment variable
.Ar name
to be
.Ar value ,
a single string.  The second form sets
.Ar name
to an empty string.
The most commonly used environment variables
.Ev USER ,
.Ev TERM ,
and
.Ev PATH
are automatically imported to and exported from the
.Nm csh
variables
.Ar user ,
.Ar term ,
and
.Ar path ;
there is no need to use
.Ic setenv
for these.
.Pp
.It Ic shift
.It Ic shift Ar variable
The members of
.Ic argv
are shifted to the left, discarding
.Ic argv Ns Bq 1 .
It is an error for
.Ic argv
not to be set or to have less than one word as value.
The second form performs the same function on the specified variable.
.Pp
.It Ic source Ar name
.It Ic source Fl h Ar name
The shell reads commands from
.Ar name .
.Ic Source
commands may be nested; if they are nested too deeply the shell may
run out of file descriptors.
An error in a
.Ic source
at any level terminates all nested
.Ic source
commands.
Normally input during
.Ic source
commands is not placed on the history list;
the \-h option causes the commands to be placed on the
history list without being executed.
.Pp
.It Ic stop
.It Ic stop % Ns Ar job ...
Stops the current or specified jobs that are executing in the background.
.Pp
.It Ic suspend
Causes the shell to stop in its tracks, much as if it had been sent a stop
signal with
.Ic ^Z .
This is most often used to stop shells started by
.Xr su  1 .
.Pp
.It Ic switch Ar (string)
.It Ic case Ar str1 :
.It \ \ \ \ \&...
.It Ic \ \ \ \ breaksw
.It \ \ \ \ \&...
.It Ic default :
.It \ \ \ \ \&...
.It Ic \ \ \ \ breaksw
.It Ic endsw
Each case label is successively matched against the specified
.Ar 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 the `default' label is found, then
the execution begins after the default label.
Each case label and the default label must appear at the beginning of a line.
The command
.Ic breaksw
causes execution to continue after the
.Ic endsw .
Otherwise control may fall through case labels and the default label as in C.
If no label matches and there is no default, execution continues after
the
.Ic endsw .
.Pp
.It Ic time
.It Ic time Ar command
With no argument, a summary of time used by this shell and its children
is printed.
If arguments are given
the specified simple command is timed and a time summary
as described under the
.Ic time
variable is printed.  If necessary, an extra shell is created to print the time
statistic when the command completes.
.Pp
.It Ic umask
.It Ic umask Ar value
The file creation mask is displayed (first form) or set to the specified
value (second form).  The mask is given in octal.  Common values for
the mask are 002 giving all access to the group and read and execute
access to others or 022 giving all access except write access for
users in the group or others.
.Pp
.It Ic unalias Ar pattern
All aliases whose names match the specified pattern are discarded.
Thus all aliases are removed by `unalias *'.
It is not an error for nothing to be
.Ic unaliased .
.Pp