Basic UNIX process

fork

In C, use fork() to fork the program into two process (i.e. copy the whole stack, heap, memory, etc.), one is parent and the other is child.

For parent, fork() will return the pid of the child.

For child, fork() will return 0.

Return type: pid_t

wait until the process with a specific pid ends

run an external program other than c

For example:

-rw-r--r--

index 0: file type index 1-3: owner index 4-6: group index 7-9: other

read write execute (rwx)