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wait

Header File

process.h

Category

Process Control Routines

Prototype

int wait(int *statloc);

Description

Waits for one or more child processes to terminate.

The wait function waits for one or more child processes to terminate. The child processes must be those created by the calling program; wait cannot wait for grandchildren (processes spawned by child processes). If statloc is not NULL, it points to location where wait will store the termination status.

If the child process terminated normally (by calling exit, or returning from main), the termination status word is defined as follows:

Bits 0-7 | Zero.
Bits 8-15 | The least significant byte of the return code from the child process. This is the value that is passed to exit, or is returned from main. If the child process simply exited from main without returning a value, this value will be unpredictable. If the child process terminated abnormally, the termination status word is defined as follows:
Bits 0-7 | Termination information about the child:

Bits 8-15 | Zero.

Return Value

When wait returns after a normal child process termination it returns the process ID of the child.

When wait returns after an abnormal child termination it returns -1 to the parent and sets errno to EINTR.

If wait returns without a child process completion it returns a -1 value and sets errno to:

ECHILD | No child process exists

Portability

POSIX | Win32 | ANSI C | ANSI C++
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