I am currently hosting my database for free on Openshift and have my program running on a linux box on my local server. I need to pass the data from the program to my openshift database. I want to run the linux box headless.
To do this I run the command:
rhc port-forward -a webapp
My question is how can I run this command permanently without it timing out (some checking to see if process is running?) and without a terminal running (background process)?
You could add that command in the startup settings of your Linux computer. So a systemd configuation, or an init one (details could depend upon your particular distribution and system). See systemd(1) and/or sysvinit
You could also use crontab(5). It can be used for periodic tasks, but also for started once tasks, thru some #reboot entry.
At last, you might use batch facilities, look into at (& batch)
Perhaps you may just want nohup(1) (or screen(1)...)
Related
I have an issue with later versions of ES, so have to use 7.10.2 currently.
This means that the previous method I used to install ES as a service, i.e. apt-get, doesn't work You can't choose an older version this way: it currently installs 7.16.3.
So I followed the procedure on this page for 7.10: everything worked: I was able to run ES as an app and also as a "daemon". Clearly I could simply put the "daemon" startup line in a script which runs on boot.
But what's the optimum way of turning this "daemon arrangement" into a service which you can control with systemctl, and which starts automatically when the machine boots?
PS I don't want to get involved with Docker. I'm sure that's a useful thing but I'm convinced there is a simpler way of doing it, using available Linux sys tools.
I found a workaround... this doesn't in fact create a service of the "systemd" type which can be controlled by systemctl. There seem to be one or two problems which make this non-trivial.
1) You can't start ES as root! I assume (not sure) that most services are being run by root. Anyway this was something I couldn't find a solution to.
2) I am not sure whether a shell script file called by a service is allowed to end... or should continue endlessly: initially I thought this would be sufficient. This is a shell script (run_es_daemon.sh) which does indeed start up ES (as a daemon process) when run by manually in a terminal. There is no issue to do with the fact that the script ends and you then close the terminal: the daemon process continues to run:
#!/bin/bash
# start ES as a daemon...
cd /home/mike/Elasticsearch/elasticsearch-7.10.2
./bin/elasticsearch -d -p pid
... but it never worked using a xxx.service file in /etc/systemd/system/ (maybe because of 1) above). So I also tried adding these lines under the above ones:
while true
do
echo "bubbles"
sleep 60
done
... didn't work either.
In the end I found a simple workaround solution was to start up the daemon process by using crontab:
#reboot /home/mike/sysadmin/run_es_daemon.sh
... but I'd still like to know how to set it up as a true service, which starts at boot...
I want my raspberry to execute 2 commands when he starts but i don't know how to setup it
the commands are
cd /var/www/restaurant && php -S 10.0.0.1:8000 -t public
i have tried to edit /etc/rc.local and add my command but it doesn't work
The "official" way to run a program at boot time on systemd-based Raspbian systems (and, in fact, most modern Linux distributions) is to create a systemd unit file. There are specific instructions for Raspbian here:
https://www.raspberrypi.org/documentation/linux/usage/systemd.md
The entry After=network.target is particular relevant in this case, because I imagine your program will need network interfaces to be up.
rc.local is a hold-over from the SysV init days, and I've heard reports of it not working reliably in Raspbian. Creating a systemd unit file provides a simple way to test the service using systemctl without actually having to reboot. If it fails on boot, you'll probably need to use journalctl to see the error messages.
NOTE: I am running Red Hat 6.7
I have a service that is configured with the Linux init system to start a process as a service when the machine boots. This was done by doing this one-time configuration from the command line:
ln -snf /home/me/bin/my_service /etc/init.d/my_service
chkconfig --add my_service
chkconfig --level 235 my_service on
When the OS reboots, the service starts as expected.
I ALSO need the service to be restarted if the service (my_service) crashes. From what I've read, all I need to do is add an entry to /etc/inittab that looks like this:
mysvc:235:respawn:/home/me/bin/my_service_starter
Where my_service_starter looks like:
#!/bin/bash
/home/me/bin/my_service start
My understanding is that when the init system detects that my_service is not running, it will attempt to restart it by running "my_service_starter".
However this does not seem to be working.
I need to understand how to tell the Linux init system to restart my service when the service crashes.
Given an entry like:
mysvc:235:respawn:/home/me/bin/my_service_starter
Then inittab will:
call /home/me/bin/my_service_starter
which will call /home/me/bin/my_service start
...and then exit, so init will thing your service has failed
so init will call /home/me/bin/my_service_starter again
...and so forth, which will result in init deciding that your script is respawning too fast, after which it will ignore it completely.
A process started by inittab is not expected to exit. If you really want to use inittab to maintain your service, you could remove /etc/init.d/my_service, and then in /etc/inittab you would have something like:
mysvc:235:respawn:/home/me/bin/my_service
And you would need to ensure that my_service runs in the foreground (some programs automatically daemonize by default, although these will often have some sort of --run-in-foreground flag).
If you upgrade to CentOS 7 or something else with systemd, this all becomes easier.
You can also investigate "third-party" process supervisors like "supervisord" or "runit" that you could use for process monitoring/restarting on CentOS 6.
Update
As mangotang points out, and I forgot, RHEL 6 actually shipped with upstart, even though it used almost exclusively SysV-style init scripts. So a better solution would be to create an upstart service instead. There are some reasonable getting-started docs here.
On RHEL 6.X, at top of the /etc/inittab file it says:
# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM
RHEL 6.X uses Upstart instead of the System V init system. See the man pages for initctl(8) and initctl(5), or ask Google about Upstart.
Multiple zabbix agent can be easily installed on windows system like this
zabbix_agentd.exe --config <configuration_file_for_instance_1> --install --multiple-agents
zabbix_agentd.exe --config <configuration_file_for_instance_2> --install --multiple-agents
...
zabbix_agentd.exe --config <configuration_file_for_instance_N> --install --multiple-agents
You can find more details on zabbix official documentation I have tried and It is working perfectly.
But, I could not find any documentation on multiple linux agents. Even I could not found any info whether it is possible or not.
I have tried running zabbix_agentd with same parameters(--install --multiple-agents) on linux. But these parameters are not valid on linux system. Or any other similar parameter exists.
So, basicly is it possible to run multiple agent on linux environment(especially centos)? And, if it is possible how?
Yes, it is possible. One should simply specify different configuration files that specify different PID files, log files, ports to listed on, etc., so that agents do not conflict with one another, similar to how you would do it on Windows.
In particular, in Unix there is a concept of a PID file. A PID file is created automatically by Zabbix agent when it starts and contains the PID of the main process. Scripts use this information to stop the currently running agent. When Zabbix agent is stopped, the PID file is automatically removed.
I have written up a simple bash script that will copy the newest image from my ip camera into a directory, rename the file and delete the old file. The script loops every 10 seconds.
I want to have this script start running in the background and run continuously all the time that the server is up.
I understand the part about adding a & to the end of the command will cause it to run in the background.
Is init.d the best place to execute this?
I am running ubuntu server.
This sort of thing is normally done by service scripts, which you would find under /etc/init.d. Depending on the version, that might be a "System V init script", or one of the systemd scripts.
A simple service script of the sort you are asking about would start automatically (based on comments in the script's header that tell what run-levels it would use), create a file under /var/run telling what process-id the script uses (to allow killing it), and run the copying in a loop, calling sleep 10 to space the timing as indicated.
A typical service script should implement "start", "stop", "restart" and "status". Not all do, but there is rarely a good reason to not do this.
On my (Debian) system, there is a README file in the directory which is a good introduction to the topic. There are several tutorials available for the topic. Here are a few:
Linux: How to write a System V init script to start, stop, and restart my own application or service
Writing a Linux Startup Script
Manage System Startup and Boot Processes on Linux with Upstart