Dora asked:
I am trying to make a crontab to start nginx if it is stopped.
I googled and found these two scripts
#!/bin/bash
service=replace_me_with_a_valid_service
if (( $(ps -ef | grep -v grep | grep $service | wc -l) > 0 ))
then
echo "$service is running!!!"
else
/etc/init.d/$service start
fi
somehow if I run it manually it works fine by doing source scriptName after I add it to crontab even if the service is stopped, it keeps on echoing nginx is running and does not start the service.
Then I found another script in digital ocean
#!/bin/sh
ps auxw | grep nginx | grep -v grep > /dev/null
if [ $? != 0 ]
then
/etc/init.d/nginx start > /dev/null
fi
again if I run it manually it works, but it will ask for the user’s password
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to start 'nginx.service'.
Authenticating as: abc,,, (abc)
after I typed in the password ==== AUTHENTICATION COMPLETE === will show and starts
nginx
then I add the script into crontab…I get this permission error
Failed to start nginx.service: Interactive authentication required.
Does anyone know how I can fix this?
Thanks in advance for any advices.
My answer:
Those scripts you have been trying to use are obsolete and shouldn’t be used on a modern system with systemd.
Try a script like this instead:
#!/bin/bash
if ! systemctl is-active nginx >/dev/null ; then
systemctl start nginx
fi
But, that is some terribly nasty hackery and probably not necessary, so before you do that, try having systemd restart nginx automatically if it stops. Do that with a systemd drop-in:
[Service]
Restart=always
which you place as the file /etc/systemd/system/nginx.service.d/override.conf (creating the directory if it doesn’t exist). You can also use systemctl edit nginx to create the file.
And of course, either creating the systemd drop-in, or putting this script in crontab, must be done as root (try using sudo -i for a long running root shell).
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