WAIT(1) User Commands WAIT(1)

wait - await process completion









wait [pid]...










wait [pid]...






wait [% jobid...]










wait










wait [job...]












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
    children of the shell, and thus cannot be waited for.






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 is 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 returns immediately and the return code is 0.








Wait for your background processes.








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 waits
    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
    waits until all of them have terminated. If one or more pid or
    jobid operands are specified that represent unknown process
    IDs (or jobids), wait treats them as if they were known
    process IDs (or jobids) that exited with exit status 127. The
    exit status returned by the wait utility is the exit status 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.








wait with no operands, waits until all jobs known to the invoking
    shell have terminated. If one or more job operands are specified, wait waits
    until all of them have completed. Each job can be specified as one of the
    following:


number


number refers to a process ID.




-number


number refers to a process group ID.




%number


number refers to a job number




%string


Refers to a job whose name begins with
  string




%?string


Refers to a job whose name contains string




%+
  

  %%


Refers to the current job




%-


Refers to the previous job






If one or more job operands is a process id or process group id
    not known by the current shell environment, wait treats each of them
    as if it were a process that exited with status 127.










The following operands are supported:


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.










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 . -exec wait ... \;










it returns immediately because there is no known process
    IDs to wait for in those environments.








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 returns the exit status of
    the second sleep in the pipeline:





  




wait <pid of sleep 31>
wait %%














See environ(7) for descriptions of the following
    environment variables that affect the execution of wait: LANG,
    LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.












The following exit values are returned by the wait built-in
    in ksh93:


0


wait was invoked with no operands. All processes
  known by the invoking process have terminated.




127


job is a process id or process group id that is
  unknown to the current shell environment.












See attributes(7) for descriptions of the following
    attributes:









  

    ATTRIBUTE
      TYPE
    ATTRIBUTE VALUE
  

  

    Interface Stability
    Committed
  

  

    Standard
    See standards(7).
  












csh(1), jobs(1), ksh(1), ksh93(1),
    sh(1), attributes(7), environ(7),
  standards(7)







  

    May 17, 2020
    OmniOS