Invoke mysql_waitpid like this:
shell> mysql_waitpid [options] pid wait_time
mysql_waitpid sends signal 0 to the process identified by pid and waits up to wait_time seconds for the process to terminate. pid and wait_time must be positive integers.
If process termination occurs within the wait time or the process does not exist, mysql_waitpid returns 0. Otherwise, it returns 1.
If the kill() system call cannot handle signal 0, mysql_waitpid() uses signal 1 instead.
mysql_waitpid supports the following options:
Display a help message and exit.
Verbose mode. Display a warning if signal 0 could not be used and signal 1 is used instead.
Display version information and exit.
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