It is a command that waits for completing any running process of given id. if the process id is not given then it waits for all current child processes to complete.
This example shows how the wait
command works :
Step-1:
Create a file named "wait_example.sh" and add the following script to it.
#!/bin/bash
echo "Wait command" &
process_id=$!
wait $process_id
echo "Exited with status $?"
Step-2:
Run the file with bash command.
$ bash wait_example.sh