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Figuring out the open network connections for processes ran by python

Posted by jpluimers on 2023/07/11

TL;DR:

pidof python | tr " " "\n" | xargs -r -n 1 lsof -i -a -e /run/user/1001/gvfs -p

Breakdown:

  • Getting the process IDs of any python process using pidof (most of my systems do not have pgrep installed):
    # pidof python
26128 12583
  • Given the above list is space separated, and xargs prefers line separated, lets replace spaces with newlines (I showed this before in Source: firewalld: show interfaces with their zone details and show zones in use):
    # pidof python | tr " " "\n"
26128
12583
  • By default, xargs squashes all input on one line:
    # pidof python | tr " " "\n" | xargs echo
26128 12583
  • To work around that, you can either use the -L 1 or -n 1 argument to keep them on separate lines:
    # pidof python | tr " " "\n" | xargs -L 1 echo
26128
12583
# pidof python | tr " " "\n" | xargs -n 1 echo
26128
12583
  • Now lsof can not only show open files, but also IP sockets (-i), and *only* those (-a), for a specific process ID (-p #). So by having the -p as last argument, xargs will append the process ID after it:
    # pidof python | tr " " "\n" | xargs -n 1 lsof -i -a -p
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs
      Output information may be incomplete.
COMMAND   PID    USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
python  12583 jeroenp    7u  IPv4 8347396      0t0  TCP 192.168.124.38:54576->192.168.124.23:1012 (ESTABLISHED)
python  12583 jeroenp    8u  IPv4 8345460      0t0  TCP 192.168.124.38:48250->192.168.124.23:http (CLOSE_WAIT)
  • The lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs is a warning not easy to workaround in a short manner as per [Wayback/Archive] privileges – lsof: WARNING: can’t stat() fuse.gvfsd-fuse file system – Unix & Linux Stack Exchange (thanks [Wayback/Archive] pabouk  and [Wayback/Archive] jmunsch):

    In your case lsof does not need to check the GVFS file systems so you can exclude the stat() calls on them using the -e option (or you can just ignore the waring):

    lsof -e /run/user/1000/gvfs

    (via: [Wayback/Archive] lsof: WARNING: can’t stat() fuse.gvfsd-fuse file system /run/user/1001/gvfs – Google Search)

    So you get this:

    # pidof python | tr " " "\n" | xargs -n 1 lsof -i -a -e /run/user/1001/gvfs -p
COMMAND   PID    USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
python  12583 jeroenp    7u  IPv4 8347396      0t0  TCP 192.168.124.38:54576->192.168.124.23:1012 (ESTABLISHED)
python  12583 jeroenp    8u  IPv4 8345460      0t0  TCP 192.168.124.38:48250->192.168.124.23:http (CLOSE_WAIT)
  • When there are no process IDs, you do not want to run lsof, and xargs has an argument just for that: -r, see my earlier post Source: -r argument to pipe (no argument for MacOS)- If no input is given to xargs, don’t let xargs run the utility – Unix & Linux Stack Exchange, so you get this
    # pidof python | tr " " "\n" | xargs -r -n 1 lsof -i -a -e /run/user/1001/gvfs -p

Via:

–jeroen

This entry was posted on 2023/07/11 at 12:00 and is filed under *nix, *nix-tools, bash, bash, Development, lsof, Power User, Scripting, Software Development, xargs. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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