So I am relatively new to Centos, version 6.2. I have a service that needs to be mnonitored as a cron job, and if it stops needs to be restarted. I have a few ideas on how to monitor it, but when it comes to getting it restarted thats when I get stuck. I also know the PiD of the service I want to monitor.
You can use supervise for this: http://cr.yp.to/daemontools/supervise.html
Put it in your crontab to launch on system start:
#reboot supervise foo
Related
I'm currently running a python script as a systemd service. Is there any way to "switch" into the service and take control of the script? The script has a menu but runs calculations in the background in another thread. Most likely not, so is there a way to run a python script 24/7, start on boot, restart on crash etc (just like systemd service) but be able to take control of it after I connect to the server via SSH, so I can manipulate the app?
One solution you could try would be to edit the systemd configuration to launch the process in screen or tmux, then attach that when logging in via SSH.
For instance, in the systemd unit, you might have:
[Service]
Type=single
ExecStart=tmux new "command"
Using Type=single will treat the tmux command as the main process, which would be killed if you stop it with systemctl stop systemprocess
The ExecStart=tmux new "command" creates a new tmux session with the command inside of it.
You can then attach to it using tmux attach as the same user the systemd unit is running as (I believe this is root by default).
I wish to know how can I schedule a custom script to run whenever I restart a service.
My use case is that I have to run several commands whenever I restart my Tomcat Service. I want to know if there is a way I can write a script and schedule it to run whenever I restart the Tomcat service.
I have setup the tomcat script as a systemd service. I am using Cent OS 7 x64.
I have been able to achieve this by creating another service and incorporating the Tomcat service's start stop in the new service. The new service acts as a wrapper service which first starts tomcat and then executes the commands that we need to run as soon as tomcat starts.
Then while stopping, it stops tomcat and runs clean up commands.
EDIT: I found another way of doing this on unix & linux stackexchange.
Simply create an new systemd .service file in /etc which includes and overrides part of the one in /lib. For example, create /etc/systemd/system/tomcat.service to contain
.include /lib/systemd/system/tomcat.service
[Service]
ExecStartPre=/home/meuh/myscripttorun some pre args here
ExecStartPost=/home/meuh/myscripttorun some post args here
Any ExecStartPre lines will be executed before the ExecStart line, and similarly any ExecStartPost will run after tomcat has started.
I have a script (twoRules.sh) which add rules to ovs plugin bridge.
The rules gets deleted when someone does service neutron-plugin-openvswitch-agent restart or reboots the system. So where should I put my scripts so that after the restart of neutron-plugin-openvswitch-agent the (twoRules.sh) scripts get executed successfully and rules remain added.
I tried putting it in /etc/init.d/neutron-plugin-openvswitch-agent file as other people suggested but this file is only called on /etc/init.d/neutron-plugin-openvswitch-agent restart and not on service neutron-plugin-openvswitch-agent restart.
You have to convert the script to a a SysV-style init script. There are many documents out there explaining about this.
http://www.debian-administration.org/article/28/Making_scripts_run_at_boot_time_with_Debian
http://www.cyberciti.biz/tips/how-to-controlling-access-to-linux-services.html
https://wiki.debian.org/Daemon
This way you can configure the script to be executed after certain services start or stop or when runlevel changes.
I need to have some processes start when the computer boots and run forever. These are not actually daemons, ie. they do not fork or demonize but they do not exit. I am currently using cron to start them using the #reboot directive like this:
#reboot /path/to/myProcess >>/logs/myProcess.log
Could this cause any problems with the cron daemon? I thought I could try nohup ... & to detach the new process from cron, like this:
#reboot nohup /path/to/myProcess >>/logs/myProcess.log &
Is this required at all?
Is there some other, preferred method to start processes at system boot? I know all Linux distributions provide config files and means to run a program as a service but I am looking for a method that is not Linux distribution specific.
http://www.somacon.com/p38.php
This article answers my question. It suggests that running daemons this way spawns two extra processes, a cron and a shell process, that live for as long as your daemon.
I tested this with linux and following the instructions I was able to get rid of the cron process but not the zombie shell process.
For example - i have process id which i want to restart. What command i should use to restart this process application ? I didn't find something about it(
Thanks!
You can find very similar question at Restart process script linux.
Linux doesn't have general command for restart, normally you should kill your process and start it over. However, if your process has been started as a service, i.e. it's contained in /etc/init.d/ directory, then you can do the following:
/etc/init.d/SERVICE_NAME restart
or
service SERVICE_NAME restart