I wrote a service script to run a specific software at boot time. How can I restrict this software so that it does not run manually again?

I mean software has to have just one instance in the memory..

I don't want to change the source code of my software, I want init to this job for me.

  • 1
    You really should add some locking in the ELF executable (i.e. change the C source code of it). Aug 18, 2014 at 16:16
  • In windows you can do that with registry :) In linux with what? Aug 18, 2014 at 17:22

5 Answers 5


This should work for a bash script. It will abort execution of the script if another instance of the external software was found. The key here is `pidof.


# Abort startup if another instance was found    
pidof /path/to/software.executable > /dev/null && {
  echo Sorry. Only one instance allowed.

Alternatively you could use lock files, replace the running instance (i.e. first kill running instance, then allow run).

An expert user could however bypass this script and invoke the external command directly.

  • Thanks for your post BUT I don't want to restrict my service script's I wanna restrict USER to not run our SOFTWARE(Command) from linux (not our software) because it has been executed. Aug 18, 2014 at 12:52
  • 2
    The code I provided will restrict USER (and everyone else) to not run the software while there is another instance running. If this is not what you want could you explain better?
    – LatinSuD
    Aug 18, 2014 at 12:58
  • That's true but I have too add these codes to the software source code but I wanna init do that for me.... Aug 18, 2014 at 13:07
  • Depending on how your users interact with your system, I would recommend only exposing them to a "launcher" script that you've written (and denying them access to the original launcher script). This script would look similar to the above answer
    – OldTinfoil
    Aug 18, 2014 at 13:25
  • pidof didn't work for me, but grepping the output of ps aux did.
    – ds-bos-msk
    Jun 1, 2023 at 3:33

You can instruct init to run only one instance of your software — in fact, that will happen naturally if you start your software from init. But init's job has nothing to do with preventing other programs from starting other instances of your software.

If you want to ensure that only a single instance of your program runs, then instead of running your program directly, run a wrapper script that checks whether your software is already running. LatinSuD's answer gives an example of such a wrapper script.

Of course a user could bypass the wrapper script and run another instance of your software. But a user could also create an executable file that happens to be identical to yours and run that. So going via a wrapper script does implement the desired restriction in a way that makes sense.

Having multiple instances of the same executable running is not in itself a problem. What can be a problem is if they access the same resource: files, network ports, etc. If you need to protect against concurrent access to the same resource, then the possible methods depend on what the resource is. If the resource is a TCP or UDP port, only one process can listen on that port anyway. If the resource is a file, make sure that only the user running the instance started by an init script has the right to access that file.


Old thread but worth to put some notes here: In case of running the process under a parent like "/bin/bash /tmp/my_script.sh" or "python my_script.py", use the following:

pgrep -l my_script.sh >/dev/null && echo "Another process is running" || { 
do your stuff;

If we're constrained to only running something with init, then the only solution I can think of is to have a lightweight kill-script constantly monitoring what processes are running, and to terminate any additional processes.

But I would suggest that this is far from perfect, and could be bypassed relatively easily.

  • (Still think that a solution based on @LatinSud 's answer is more elegant)
    – OldTinfoil
    Aug 18, 2014 at 13:25

Actually, the sensible way is to deny a user access by using the correct permissions and only allow root(esque) users run the software.

  • BTW, you could use crontab jobs to periodically restrict permissions on some file. Aug 18, 2014 at 17:28
  • Depending on how time-critical it is to ensure that no additional processes are running...
    – OldTinfoil
    Aug 18, 2014 at 17:30
  • It's very critical job... Aug 18, 2014 at 18:32
  • I suggest looking at my other answer, if that's the case
    – OldTinfoil
    Aug 18, 2014 at 18:46

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .