What Will Be When I Die?

When a process dies, a CHLD signal is sent to its parent. The parent then needs to use the 'wait' system call to clean-up after its child.

Until the parent issues this 'wait' call, the child's process table entry is NOT freed, and the child is placed into a state called 'zombie'. In the output of 'ps' the child's command will appear as '<defunct>'.

Normally, when a process exits, all the resources it uses are automatically cleaned up by the OS - memory pages are freed, open files are closed, etc. Note that data written to buffer output channels (e.g. stdout) does NOT necessarily get written out, and might be lost.