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Full Discussion: How do I check if a process is running in C
Top Forums Programming How do I check if a process is running in C Post 302461706 by Praveen_218 on Tuesday 12th of October 2010 05:01:00 AM
Old 10-12-2010
Use pidof instead ...
You may want to use pidof. This prints the pid of the running process on the stdout.

Usually its available at path /sbin/pidof; hence either you need to be the superuser or have the read access.

The command is
Code:
Your Prompt] # pidof -x <your process name>

Use as below in your C code (although not advices to use the system(<cmd>) in a C code but then you already used the same):
Code:
int
main() {
   /*
   ** Code snippet.
   */
   if(0 == system("pidof -x PROCESS > /dev/null")) {
      //A process having name PROCESS is running.
   }
   else if(1 == system("pidof -x PROCESS > /dev/null")) {
      //A process having name PROCESS is NOT running.
   }

   /*
   ** Continue processing further.
   */
return STATUS;
}

Look at the return value to decide on its running status. You can get this by executing, from the command prompt, another command 'echo $?' immediately after executing the pidof.
 

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LEARN ABOUT POSIX

pidof

PIDOF(8)						Linux System Administrator's Manual						  PIDOF(8)

NAME

       pidof -- find the process ID of a running program.

SYNOPSIS

       pidof [-s] [-c] [-n] [-x] [-o omitpid[,omitpid..]]  [-o omitpid[,omitpid..]..]  program [program..]

DESCRIPTION

       Pidof  finds  the  process  id's (pids) of the named programs. It prints those id's on the standard output. This program is on some systems
       used in run-level change scripts, especially when the system has a System-V like rc structure. In that case these scripts  are  located	in
       /etc/rc?.d, where ? is the runlevel. If the system has a start-stop-daemon (8) program that should be used instead.

OPTIONS

       -s     Single shot - this instructs the program to only return one pid.

       -c     Only  return  process ids that are running with the same root directory.	This option is ignored for non-root users, as they will be
	      unable to check the current root directory of processes they do not own.

       -n     Avoid stat(2) system function call on all binaries which are located on network based file systems like NFS.  Instead of using  this
	      option the the variable PIDOF_NETFS may be set and exported.

       -x     Scripts too - this causes the program to also return process id's of shells running the named scripts.

       -o omitpid
	      Tells  pidof  to omit processes with that process id. The special pid %PPID can be used to name the parent process of the pidof pro-
	      gram, in other words the calling shell or shell script.

EXIT STATUS

       0      At least one program was found with the requested name.

       1      No program was found with the requested name.

NOTES

       pidof is actually the same program as killall5; the program behaves according to the name under which it is called.

       When pidof is invoked with a full pathname to the program it should find the pid of, it is reasonably safe. Otherwise it is  possible  that
       it  returns  pids  of  running programs that happen to have the same name as the program you're after but are actually other programs. Note
       that that the executable name of running processes is calculated with readlink(2), so symbolic links to executables will also match.

SEE ALSO

       shutdown(8), init(8), halt(8), reboot(8), killall5(8)

AUTHOR

       Miquel van Smoorenburg, miquels@cistron.nl

								    01 Sep 1998 							  PIDOF(8)
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