kill -HUP: Reload a Daemon's Config Without Restarting
Send SIGHUP to a daemon by PID to ask it to re-read its configuration file in place.
Run sudo kill -HUP <PID> (e.g. sudo kill -HUP $(pgrep sshd)) to ask the daemon to reload its configuration without stopping it.
01Command
Command
$ sudo kill -HUP $(pgrep sshd)02What it does
SIGHUP originally meant "hangup detected on the controlling terminal", but many daemons have adopted it as a convention for "re-read your config now" — classic examples are sshd, nginx, and syslog daemons. It works only for daemons that explicitly handle SIGHUP; for others it is just a normal signal and may terminate the process, and for systemd-managed services systemctl reload <unit> is the better route. After sending it, check the daemon's log to confirm the reload actually happened.
03Risk
!Warning: SIGHUP is a per-daemon convention, not a guarantee — verify in the program's man page that HUP means reload before sending it, otherwise you may simply kill the daemon.
04Undo
✓No undo needed — this command does not change persistent state.
05Sources
- Ubuntu Manpage: kill - terminate or signal processesEvidence: The kill utility sends the specified signal to processes by PID; the signal list includes SIGHUP ("hangup") and the -<signal> form, e.g. kill -HUP <pid>.
- kill - send a signal to a processEvidence: kill sends signals to processes by PID; "1) SIGHUP" appears in the standard signal table and the -s/-<signal> option selects which signal to send.
Last verified: 2026-09-19 · Category: System & Settings