How to wake up sleeping process?

Question

Shell script runs two functions as child processes (via &).
Both of them went to sleep (via sleep command).

Is it possible to wake them?

I have their pids.

P.s.

I don't want to run sleep with & and wait

Answer 1

A rather barbaric way to do this would be to kill the sleep process (not the whole subshell in which your script/function runs). Consider the following shell script:

#!/bin/bash
sleep 20
echo "Done!"

or, with a function:

#!/bin/bash

function gotosleep()
{
    sleep 20
    echo "Done!"
}

gotosleep &
sleep 60 # Not really necessary, keeps the script in foreground.

Then, find the sleep process:

$ ps -ef | grep sleep
you    PID    PGID  ... sleep 20

And kill it:

$ kill PID

You script will then output (at least in bash):

./script.sh: line 2: PID Terminated    sleep 20
Done!

Since you don't want to wait properly, you'll have to do with Bash's little message. If you change your mind, have a look at this question:

sleep 20 &
if wait $! 2>/dev/null; then
    # Keep working
    continue
else
    echo "Done!"
    return # from function
fi