The wait system-call puts the process to sleep and waits for a child-process to end. It then fills in the argument with the exit code of the child-process (if the argument is not NULL).
What is the difference between a wait() and sleep() in Threads? Is my understanding that a wait() -ing Thread is still in running mode and uses CPU cycles but a sleep() -ing does not consume any CPU cycles correct? Why do we have both wait() and sleep()? How does their implementation vary at a lower level?
Difference between "wait ()" vs "sleep ()" in Java - Stack Overflow
man wait (2) All of these system calls are used to wait for state changes in a child of the calling process, and obtain information about the child whose state has changed. A state change is considered to be: the child terminated; the child was stopped by a signal; or the child was resumed by a signal So wait() allows a process to wait until one of its child processes change its state, exists ...
What is difference between wait and sleep? Note that sleep and wait can be very powerful in conjunction, if you want your bash script to wait until it receives a signal. The following script will stop waiting for the sleep to finish if it receives one of the trapped signals. With just the sleep alone, the signal wouldn't be encountered until the sleep has finished.
I have read that we should always call a wait() from within a loop: while (!condition) { obj.wait(); } It works fine without a loop so why is that?