Check if daemon is running linux

How to check if a daemon service is running via Cron job or script?

How can I set up a cron job to monitor multiple PIs (via SSH) that are running the same daemon script (service)? I was thinking of using a cron job to monitor the service status and write to a file on my server if the status of the service is active or inactive, and then I can later use the contents of that file to display the results of the Cron job onto a web page (but that is for me to figure out later). I’m open to other options if someone can figure out an easier way using a different tool, E.g. bash script, python script, PHP etc,

2 Answers 2

How to check if a daemon service is running

in RHEL/CentOS v4.x/5.x/6.x and Fedora Linux (older version) Verify Cron Service You can simply use any one of the following command to see if crond is running or not, enter:

# crond (pid 4370) is running. 

If it is not running type the following two command to start crond:

$ chkconfig crond on $ service crond start 

Verify cron is running by viewing log file, enter:

A note about CentOS/RHEL v7.x+ and latest version of Fedora Linux You need to use the following command to find out if the crond is running or not:

$ systemctl status crond.service 

Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled) Active: active (running) since Tue 2015-05-19 14:53:32 EDT; 3min 7s ago Main PID: 1292 (crond) CGroup: /system.slice/crond.service └─1292 /usr/sbin/crond -n 

If not running configure the crond service to start automatically on boot:

$ sudo systemctl enable crond.service $ sudo systemctl start crond.service 

A note about Debian / Ubuntu Linux (older version) Cron service On a Debian and Ubuntu Linux cron logs its action logged to the syslog facility i.e. use /var/log/messages file:

Find out if cron daemon is running or not, enter:

If not running start it, enter:

$ update-rc.d cron defaults $ /etc/init.d/cron start 

A note about Debian Linux v8.x+ and latest version of Ubuntu Linux The syntax is as follows to check if the cron service is running or not:

◠cron.service - Regular background program processing daemon Loaded: loaded (/lib/systemd/system/cron.service; enabled) Active: active (running) since Tue 2015-05-19 11:49:32 IST; 12h ago Docs: man:cron(8) Main PID: 1053 (cron) CGroup: /system.slice/cron.service ├─1053 /usr/sbin/cron -f └─3020 /usr/bin/atop -a -w /var/log/atop/atop_20150520 600 

If not running configure the crond service to start automatically on boot:

$ sudo systemctl enable cron.service $ sudo systemctl start cron.service 

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How to Verify if Docker Daemon is Running

Docker is a software designed to package software and then transport software in the form of containers. The Docker Daemon is the process that is running in the background of your system, and this process keeps track of and manages the containers on that host.

To keep using Docker, the Docker daemon must run in an active state on the system. In this post, we will demonstrate multiple methods to verify the Docker daemon running.

How to Verify if Docker Daemon is Running?

It is important to know the current status of your Docker Daemon while working on the Docker containers. There exist a couple of different ways in which the status of your Docker can be checked. Let’s dig into them:

Method 1: Use the systemctl command

In Linux, the “systemctl” utility is practiced to check the status of services running on the system. For checking the current status of the Docker daemon, execute the command shown below Linux terminal:

$ sudo systemctl status docker

The “Active” tag shows whether the Docker is currently running or not. If the tag shows other than “Active” status, the Docker daemon is not functioning properly.

In such a situation, the users can start the Docker daemon as follows (this may not be considered the only solution to the inactive status):

Since Docker Daemon is already running on our system, this error is displayed otherwise if it is inactive, this command will activate it.

Method 2: Check the Process ID of Docker Daemon

Since the Docker Daemon is a process, it will have a process ID if it is currently running in the background. To get the process ID for Docker Daemon, run the “pidof” command to get the ID of “dockerd”:

Since the command above is displaying the process “ID” for the “dockerd” process, this verifies that the Docker Daemon is currently running on your system.

Conclusion

There are “two” ways for evaluating whether the Docker Daemon is operating or not. The first is to use the “systemctl” command, and the second is to check the “process ID” of “dockerd”. The “active” status from the “systemctl” command shows that the Docker daemon is running. While the process ID ( using the “pidof”) is the proof that the Docker daemon is running. This article has explained how to verify Docker daemon is running.

TUTORIALS ON LINUX, PROGRAMMING & TECHNOLOGY

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UNIX for Dummies Questions & Answers

1, 0

Does anyone know if there is a UNIX-tool available that constantly will check if (some specific) deamons are running and will notify (via email) if one has failed/stopped?
I searched the web, but so far didn’t find anything.

670, 4

To mannually check the deamon what you can do is
type $ ps -ef | grep if its running it will show the process with a pid. If its not you may try to
$ /etc/init.d/ [start|stop|restart]. This is only a mannual way instruction i never did a daemon process stop alarm thru mail. Perhaps some others might have some idea.

262, 2

send an email if process fails

this can be done by writing a shell script
I have choosen to write this in korn shell
———————————————

PROCESSCOUNT=$(ps -ef |grep -v grep |grep -cw

if [ $PROCESSCOUNT -eq 0 ]
then
mailx -s «daemon process not running» myaddress@mydomain

———————————————
place the above script in crontab and schedule it
to run every 5 mins depends on how soon you want to be notify

please let me know the out come of the above solution.

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How to check whether the Docker Daemon or the container is running?

While using Docker, you need to check if the daemon is running or not in order to diagnose the issues with the container and the docker order.

In this tutorial, you are going to know how to check whether the Docker Daemon or container is running or not.

Check the status using systemctl

Distributions like Debian, Ubuntu, CentOS, and Red Hat use Systemd for service management. In this Systemd there’s a Systemctl command, this is a command utility used to examine and control the Systemd and the system manager. You can check whether the Docker daemon is running using the following command —

sudo systemctl status docker

The command will return the status of the docker daemon which will look like this :

Now, check what is being displayed in the «Active». If there is active (running) in green then the Docker daemon and containers should be running.

If there is «inactive» then it indicates that the docker daemon is stopped. you can start it using the following command —

sudo systemctl start docker

If you see the status as «failed» in red then the docker is unable to start due to an error. You can start the Docker daemon in debugging mode to see what’s wrong —

Inspecting the Process ID file

Whenever the Docker daemon starts, it writes its process ID to /var/run/docker.pid. You can use this process ID to check whether the Docker daemon is running or not.

You can create various programming scripts using this technique to check the docker daemon’s status. When you read the process Id from the file, you can use tools like top which shows the Linux processes to get the information about the docker daemon.

cat /var/run/docker.pid # when the process -p 1000

this will return the following information as the output —

You can get the process ID with the «pidof» the command which accepts a process name —

pidof dockerd #information with top top -p `pidof dockerd`

If the top matches the dockerd process then the docker daemon is running.

Checking Individual Containers

You can check the status of individual containers, and whether they are running or not. The command docker ps shows the table which contains all the information of the running containers.

The output of this command should look like this —

You can combine the docker ps command with the grep keyword to check the status of a specific container by its name or ID. There will be no record if the container is not running.

docker ps | grep container-name

You can start the stopped container using the start command —

docker start container-name

Conclusion

Checking the status of the Docker daemon and the containers is important for diagnosing issues and ensuring that everything is running smoothly in a Docker environment.

In this tutorial, we have learned different ways to check whether the Docker daemon is running, such as using the systemctl command, inspecting the process ID file, and checking the status of individual containers using the docker ps command. By using these methods, you can quickly identify any issues with the Docker environment and take appropriate action to resolve them.

Frequently Asked Questions

1. How can I check if the Docker daemon is running?

You can check if the Docker daemon is running on Linux-based operating systems by using the systemctl command which checks the status of the Docker daemon: sudo systemctl status docker.

2. How do I check the status of a specific container?

To check the status of a specific container you can use the docker ps command to list all running containers and filter them using grep to show the specific container you’re interested in.

3. How do I start a stopped container?

You can start a stopped container using the docker start command followed by the container ID or name. For example, to start a container named «my-container», you can use the command: docker start my-container.

4 Can I use these methods to check if the Docker daemon or container is running on all operating systems?

No, you can not use these methods to check if the Docker daemon or container is running on all operating systems as these methods are specific to Linux distributions. The methods may differ for other operating systems, such as macOS or Windows which you can explore on studytonight.

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