wait(1) User Commands wait(1)NAMEwait - await process completion
SYNOPSIS
/bin/sh
wait [pid]...
/bin/jsh /bin/ksh /usr/xpg4/bin/sh
wait [pid]...
wait [% jobid...]
/bin/csh
waitDESCRIPTION
The shell itself executes wait, without creating a new process. If you
get the error message cannot fork,too many processes, try using the
wait command to clean up your background processes. If this doesn't
help, the system process table is probably full or you have too many
active foreground processes. There is a limit to the number of process
IDs associated with your login, and to the number the system can keep
track of.
Not all the processes of a pipeline with three or more stages are chil‐
dren of the shell, and thus cannot be waited for.
/bin/sh, /bin/jsh
Wait for your background process whose process ID is pid and report its
termination status. If pid is omitted, all your shell's currently
active background processes are waited for and the return code will be
0. The wait utility accepts a job identifier, when Job Control is
enabled (jsh), and the argument, jobid, is preceded by a percent sign
(%).
If pid is not an active process ID, the wait utility will return imme‐
diately and the return code will be 0.
csh
Wait for your background processes.
ksh
When an asynchronous list is started by the shell, the process ID of
the last command in each element of the asynchronous list becomes known
in the current shell execution environment.
If the wait utility is invoked with no operands, it will wait until all
process IDs known to the invoking shell have terminated and exit with
an exit status of 0.
If one or more pid or jobid operands are specified that represent known
process IDs (or jobids), the wait utility will wait until all of them
have terminated. If one or more pid or jobid operands are specified
that represent unknown process IDs (or jobids), wait will treat them as
if they were known process IDs (or jobids) that exited with exit status
127. The exit status returned by the wait utility will be the exit sta‐
tus of the process requested by the last pid or jobid operand.
The known process IDs are applicable only for invocations of wait in
the current shell execution environment.
OPERANDS
The following operands are supported:
One of the following:
pid The unsigned decimal integer process ID of a command, for
which the utility is to wait for the termination.
jobid A job control job ID that identifies a background process
group to be waited for. The job control job ID notation is
applicable only for invocations of wait in the current shell
execution environment, and only on systems supporting the job
control option.
USAGE
On most implementations, wait is a shell built-in. If it is called in a
subshell or separate utility execution environment, such as one of the
following,
(wait)
nohup wait ...
find . -execwait ... \;
it will return immediately because there will be no known process IDs
to wait for in those environments.
EXAMPLES
Example 1 Using A Script To Identify The Termination Signal
Although the exact value used when a process is terminated by a signal
is unspecified, if it is known that a signal terminated a process, a
script can still reliably figure out which signal is using kill, as
shown by the following (/bin/ksh and /usr/xpg4/bin/sh):
sleep 1000&
pid=$!
kill -kill $pid
wait $pid
echo $pid was terminated by a SIG$(kill -l $(($?−128))) signal.
Example 2 Returning The Exit Status Of A Process
If the following sequence of commands is run in less than 31 seconds
(/bin/ksh and /usr/xpg4/bin/sh):
sleep 257 | sleep 31 &
jobs -l %%
then either of the following commands will return the exit status of
the second sleep in the pipeline:
wait <pid of sleep 31>
wait %%
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables
that affect the execution of wait: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│Standard │See standards(5). │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOcsh(1), jobs(1), ksh(1), pwait(1), sh(1), attributes(5), environ(5),
standards(5)SunOS 5.10 19 Apr 2010 wait(1)
