wait commands(7.15)

WAIT COMMAND:
In computing, wait is a command which pauses until execution of a background process has ended.

Usage:

 wait [n]

where n is the pid or job ID of a currently executing background process (job). If n is not given, the command waits until all jobs known to the invoking shell have terminated.
wait normally returns the exit status of the last job which terminated. It may also return 127 in the event that n specifies a non-existent job or zero if there were no jobs to wait for.
Because wait needs to be aware of the job table of the current shell execution environment, it is usually implemented as a shell builtin.