CompTIA Linux+ XK0-006 (V8) Practice Question

The shell built-in exec overlays the current shell with the specified program; it does not fork a new process, so the PID remains the same and control never returns to the shell after the replacement command ends. Writing exec /usr/local/bin/backup.sh therefore makes the cron-started Bash process turn into backup.sh, eliminating the extra sleeping shell.

All other choices start a new process:

• Running with nohup and an ampersand spawns a child process that survives hang-ups but leaves the parent shell intact.
• Using an ampersand followed by disown also backgrounds the job, then detaches it from the shell-yet the shell process still exists until it exits.
• env -i starts a command with an empty environment but, like any ordinary command, is executed in a child process forked from the shell.

Only the exec form replaces the current shell in-place.