How to find the .pid file for a given process
Solution 1
You'll usually find the PID files for daemonized processes in /var/run/
on Redhat/CentOS-style systems.
Short of that, you can always look in the process init script. For instance, the SSH daemon is started with the script in /etc/init.d/sshd
. Sometimes the PID will be defined there (search for pid, PID, PIDFILE, PID_FILE, etc.).
However, most other daemons on RHEL-style systems source the /etc/init.d/functions
script for some common features.
# Set $pid to pids from /var/run* for {program}. $pid should be declared
# local in the caller.
# Returns LSB exit code for the 'status' action.
__pids_var_run() {
local base=${1##*/}
local pid_file=${2:-/var/run/$base.pid}
For anything that sources /etc/init.d/functions
, the PID will live in /var/run/*.pid
.
For custom applications, the PID will be defined in a wrapper script (hopefully). Most developers I know follow the same convention as the daemons above, though.
If you do encounter something without a PID file, remember that Monit can monitor on a process string patern as well.
Solution 2
Another approach I took:
I have a database server running in embedded mode, and the data are within the containing application's directory.
The database has something like a .pid file, but it calls it lock file. To locate this lock file, I listed all files held open by the app:
$ ls -l /proc/18264/fd | cut -d'>' -f2
That gave me a long list including sockets, pipes, server files etc. Few filters and I got to what I needed:
$ ls -l /proc/18264/fd | cut -d'>' -f2 | grep /home/ | cut -b40- | sort | uniq | grep titan
/windup/reports/group_report.LJfZVIavURqg.report/graph/titangraph/00000000.jdb
/windup/reports/group_report.LJfZVIavURqg.report/graph/titangraph/je.info.0
/windup/reports/group_report.LJfZVIavURqg.report/graph/titangraph/je.info.0.lck
/windup/reports/group_report.LJfZVIavURqg.report/graph/titangraph/je.lck
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Yarin
Updated on September 18, 2022Comments
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Yarin over 1 year
I'm setting up monit and want to monitor a given python application. Monit does this by looking at the .pid files for processes, but I don't know where this would be.
I also tried creating my own simple executable and running it- here too I can't figure out where the .pid file is created.
And do all processes have a .pid file?
-
bahamat over 11 yearsNot all processes have a
.pid
file. The application (or its start up script) needs to explicitly create one.
-
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Yarin over 11 yearsewwhite- Thanks a lot- but when I try
monit procmatch anything
on the commandline I getmonit: invalid argument -- procmatch
. Any ideas? -
ewwhite over 11 yearsWhat version of Monit are you using? (Type
monit -V
) Which OS/distribution? -
Yarin over 11 yearsMonit 5.1.1 yummed onto CentOS 6
-
Yarin over 11 yearsAlso, what would be my options for multiple non-daemon processes? What do you think about this answer
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ewwhite over 11 years@yarin It looks like you have the Monit from the EPEL repository. The version for EL6 from RPMForge is 5.4.
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Yarin over 11 yearsThanks- changed repos and upgrades- procmatch works. To confirm though, this would only be for single, daemonized processes- correct?