I was debugging a strange problem with a printer server running CUPS the other day. The web admin interface (which executes the script /usr/lib/cups/cgi-bin/admin.cgi via CGI) was returning a 500 “Internal Server Error”, while running lpadmin or lpstat would return Bad file descriptor. Using strace on the script locally on the server, it could be seen that the attempt to connect to the control socket /var/run/cups/cups.sock was failing with ECONNREFUSED. Huh? Seems like CUPS forgot about the socket, so issue service cups restart. Well, that didn’t fix it either.
To make a long story short, when running with systemd, the /lib/systemd/system/cups.socket control file causes systemd itself to own the socket, and to pass it to CUPS inetd-style when the CUPS process is created. Unfortunately, if that socket gets into a bad state, it will be impossible to communicate with the CUPS child process of systemd through the socket.
# systemctl restart systemd.socket
# service cups restartThe socket will be refreshed and the newly working socket will then be passed to the CUPS child process when it is re-created.
Hello there,
If you type systemctl stop cups – you will get a message:
Warning: Stopping cups.service, but it can still be activated by:
cups.path
cups.socket
If you then type:
systemctl stop cups.path and systemctl cups.socket they will stop. You can then issue the systemctl disable cups.service. This will stop cups 100%
try to enable it:
systemctl enable cups.service
systemctl start cups.service
systemctl start cups.path
but when you issue the command:
systemctl start cups.socket you will get:
Job for cups.socket failed. See “systemctl status cups.socket” and “journalctl -xe” for details.
systemctl status cups.socket
? cups.socket – CUPS Printing Service Sockets
Loaded: loaded (/usr/lib/systemd/system/cups.socket; enabled; vendor preset: enabled)
Active: inactive (dead)
Listen: /var/run/cups/cups.sock (Stream)
I can fix it by rebooting the system… but how to solve this without rebooting…?
I learned that after a while, like 5 minutes or so, if you try to start the cups.socket service it works… really weird ….
Even I faced the same issue and couldn’t restart cups.socket since Socket service cups.service already active, refusing.
The solution is:Remember to Follow the order.
systemctl stop cups.socket
systemctl stop cups.path
systemctl stop cups.service
Wait for 3-5 minutes
Now start the services:
systemctl start cups.socket
systemctl start cups.path
systemctl start cups.service
systemctl status cups.path cups.service cups.socket