Linux start script on startup

How to run script on startup using systemd in Linux

Table of Contents

In this article I will share a sample systemd unit file which you can use to run script at startup with systemd without using crontab in RHEL/CentOS 7/8 Linux.

Some more articles on similar topic:

• How to execute a command or script with systemd at shutdown only and not at reboot in Linux
• How to execute a command or script with systemd right before login prompt appears on terminal in Linux
• How to execute a command or script at system startup using systemd without using cronjob in Linux
• How to execute a command or script after N minutes of boot up (system startup) with systemd in Linux
• How to halt system reboot or shutdown and read user input during boot up stage in Linux
• How to execute a command or script using systemd right before shutdown happens in Linux
• How to run a service as a specific user or group using systemd in Linux

There can be various scenarios when you expect a script or command to be called at startup such as

• Execute a script after waiting for N minutes of startup
• Execute a script after all the systemd services are loaded
• Execute a script immediately after login prompt appears
• Execute a script just before the login prompt appears

In this article I will cover below two topics as they are almost similar

• Run script at startup with systemd after network is reachable
• Execute script at starup after all the systemd services are loaded

I will be using CentOS/RHEL 7/8 Linux node to verify the steps from this article to run script with systemd right before login prompt.

Step 1: Overview on systemd

I hope you are already familiar with below topics

Step 2: Create Sample Script

Now to run script at startup with systemd firstly we need a script or command. For the sake of this article I have create a dummy shell script /tmp/startup_script.sh which we will use for testing this article.

This script will continue to run for 5 minutes and will print an echo statement on the screen every minute as a broadcast message using wall command for all Linux users on the respective node. And at the end of 5th minute it will print a completed broadcast. With this we can also make sure that the script is not killed by systemd if it continues to run for 5 minutes .

Provide executable permission to the script

Enable the service to make sure this is called automatically after reboot

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Executing Commands and Scripts at Reboot & Startup in Linux

There might arise a need to execute a command or scripts at reboot or every time when we start our system. So how can we do that, in this tutorial we are going to discuss just that. We will discuss how we can make our CentOS/RHEL and Ubuntu systems to execute a command or scripts at reboot or at system startup using two different methods. Both the methods are tested and works just fine,

Method 1 – Using rc.local

In this method, we will use ‘rc.local’ file located in ‘/etc/’ to execute our scripts and commands at startup. We will make an entry to execute the script in the file & every time when our system starts, the script will be executed.

But we will first provide the permissions to make the file /etc/rc.local executable,

$ sudo chmod +x /etc/rc.local

Next we will add the script to be executed in the file,

$ sudo vi /etc/rc.local

& at the bottom of file, add the entry

sh /root/script.sh &

Now save the file & exit. Similarly we can execute a command using rc.local file but we need to make sure that we mention the full path of the command. To locate the full command path, run

$ which command

$ which shutter

/usr/bin/shutter

For CentOS, we use file ‘/etc/rc.d/rc.local’ instead of ‘/etc/rc.local’. We also need to make this file executable before adding any script or command to the file.

Note:- When executing a script at startup, make sure that the script ends with ‘exit 0’.

Method 2 – Crontab method

This method is the easiest method of the two methods. We will create a cron job that will wait for 90 seconds after system startup & then will execute the command or script on the system.

To create a cron job, open terminal & run

$ crontab -e

& enter the following line ,

@reboot ( sleep 90 ; sh /location/script.sh )

where /location/script.sh is the location of script to be executed.

So this was our tutorial on how to execute a script or a command when system starts up. Please leave your queries, if any , using the comment box below.

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Shusain

Passionate about Linux & open source. Loves to learn, read & write about Linux as well as new technologies.

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15 Comments

Hello, are the slahes and backslashes correct?
@reboot ( sleep 90 ; sh \location\script.sh )
or
@reboot ( sleep 90 ; sh /location/script.sh )

Thanks for pointing out , it should be ‘/location/script.sh’.
Updating the article.

Hi, Thanks for this helpful information.
I’ve installed TightVNC on my (headless) file server which is running Ubuntu 18.04 LTS 64bit.
I start the vnc server with,
$ vncserver -geometry 1280×720 -depth 24
New ‘X’ desktop is krt1293:1

Starting applications specified in /home/bob/.vnc/xstartup
Log file is /home/bob/.vnc/krt1293:1.log

OK.
I’m accessing it from my main PC (Xubuntu 16.04 LTS 64bit) using Reminna.
I run,

$ ssh -L 5901:localhost:5901 -N -f -l USER IP

I then am able to connect using Remmina with settings,
Protocol: VNC – Virtual Network Computing
Server: localhost:5901

The connection is established and all is working OK to this point.
I then decided to setup so vncserver is started at bootup using a crontab.

Opened user crontab file with,
$ crontab -e
Added the following line at the bottom and saved,
@reboot sleep 90 ; sh /location/script.sh
Rebooted – cron failed to start vncserver
Edited the following line at the bottom and saved,
@reboot sleep 90 ; sh /location/script.sh

Rebooted – cron failed to start vncserver
Edited the following line at the bottom and saved,
@reboot (vncserver -geometry 1280×720 -depth 24 :1)
Rebooted – cron failed to start vncserver
Edited the following line at the bottom and saved,
@reboot ( vncserver -geometry 1280×720 -depth 24 :1 )
Rebooted – cron failed to start vncserver
I added a new job to the crontab to confirm that the crontab is being executed at startup,
@reboot ( touch /home/bob/tmp/cron_test )

The “vncserver” crontab failed, but the “touch” crontab was successful. Any thoughts on what I’m doing wrong?
Harry

Try again with full path to vncserver i.e. ‘/usr/bin/vncserver’. In the meanwhile i will try to replicate it on one of my machines.

I have to activate my wifi hardware each time that I reboot my system with this command ’sudo modprobe -v b43’ and I am looking to make this task easier, do you think that I can give sudo privileges?

thanks for your time and help

A quick Google search with “Persistent Module Loading” as search terms will give you the solution you need.
Also i will be posting an article for the same in coming weeks.

i need to run qt exicutble file in auto boot
crontab -e
@reboot /home/ssbc/Desktop/layout1

layout1 is qt exe file

Hi, how do you exit the crontab editor?

:wq, like we exit out in vi/vim editor.

If the script.sh file is executable, is the sh command necessary?
Would @reboot ( sleep 90 ; /location/script.sh ) work?

I need to run a script at startup, the script is located in root directory and in crontab I have added the line @reboot /root/vm_subnet.sh
but it does not run the script at reboot or startup (i guess they are both the same from a boot-up cycle POV). Am I doing something wrong here? Any syggestions?

crontab is user-dependent / user-based. Does your user have root access?

Its user dependent but to be able run scripts on startup you should have root access.

crontab is user-dependent / user-based. Does your user have root access?

Its user dependent but to be able run scripts on startup you should have root access.

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Three ways to create a startup script in Ubuntu

• 

In this post, I will introduce three ways to create a startup script in Ubuntu: systemd ( systemctl command), cron job ( @reboot directive), and shell startup script ( .bash_login , .bashrc , . ).

Suppose that the script to run is at /home/transang/startup.sh .

Method 1 (most reliable): Create a systemd startup service

Create a systemd unit file with .service extension in /etc/systemd/system , for example /etc/systemd/system/my-service.service , with the following content.

Lines starting with # can be truncated. Hence, the above unit file is equivalent to:

You can now start/stop this service with systemctl start my-service / systemctl stop my-service .
To enable this service when startup, run systemctl enable my-service .

Refer to this digital ocean post for more detail on the systemd unit file structure.

Method 2 (unreliable): Add a startup cron job

Add a crontab line with the repeat section as @reboot , i.e., run crontab -e and append the following line to the opened file.

Nonetheless, this approach is not reliable. Not only is there a bug in some Debian variants, but the behavior of the @rebooot cron job is also inconsistent between reboots and shutdowns/starts. Therefore, I will not discuss other perspectives such as when the @reboot cron job gets executed, where it is stored, who the user is running it, or whether this cron job gets executed with a sudoer privilege.

Cron is not always installed by default in some Linux distributions (such as Arch Linux) and requires a manual installation.

Method 3 (inconsistent): Create a shell startup script

You can refer to this related post to read about startup scripts and their execution order.

A side note: after reading the post mentioned above, you will realize that it is unsure whether a bash startup script is executed, when it is executed (is it run before or after you log in to the graphical screen?).
This behavior also varies significantly on the graphical program (gnome, unity, kdm, . etc.), even from version to version.

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