exec

exec [command]

Execute command in place of the current process (instead of creating a new process). exec is also useful for opening, closing, or copying file descriptors.

Examples

trap 'exec 2>&-' 0	Close standard error when 
	shell script exits (signal 0).
$ exec /bin/csh	Replace Bourne shell with C shell.
$ exec < infile	Reassign standard input to infile.