I have an application that during installation runs a bunch of processes via screen, so I can see those if attached to the screen, however I don't see those via "ps -ef" or "ps auxww". How can I list all the processes running inside of screen ?


3 Answers 3

start cmd: # screen -ls
There is a screen on:
        24525.pts-0.syscontrol  (Attached)
start cmd: # pstree -p 24525
  • Installation of pstree on Linux: apt-get install psmisc (Debian) or yum install psmisc (CentOS) Feb 21, 2020 at 6:23

Using pstree greatly simplifies the problem, but some clarification might help.

When you start screen, it runs two processes, screen (the parent) and SCREEN (the child):

  • The -ls option of screen shows the session identifier with the child's process-id.
  • You should list the parent process-id for consistency.
  • It helps to show the argument list; pstree can do this.
  • You could have multiple screen sessions on the same machine.

Tying these together calls for a script. Here is an example:

# $Id: ps-screen,v 1.1 2016/10/23 22:19:56 tom Exp $
# http://unix.stackexchange.com/questions/172347/list-processes-running-inside-of-screen-manager-with-with-vt100-ansi-terminal-e
screen -ls | awk '/[0-9]+\./{print;}' | while read session
    child=$(echo "$session" | awk '{sub("\..*","",$1); print $1;}')
    printf '%s\n' "$session"
    parent=$(ps -p $child -o ppid=)
    pstree -p -a $parent

and example output, for two sessions:

~ (101) ps-screen 
38142.pts-1.vmw-debian7-64      (10/23/2016 06:20:28 PM)        (Attached)
          └─ps-screen,38161 /users/tom/bin/ps-screen
              └─ps-screen,38164 /users/tom/bin/ps-screen
                  └─pstree,38169 -p -a 38141
3975.pts-0.vmw-debian7-64       (10/23/2016 06:15:28 AM)        (Attached)
      │   └─ded,19926 /usr/build//ncurses
      │       └─vile,24647 /usr/build/ncurses/ncurses-6.0-20161029/NEWS
          └─ded,36569 /tmp

Further reading:


Retrieve tty(pty) from screen -ls and then, ps -t ttyname or ps t ttyname will display process list associated with ttyname.

ps(1) manpage on Ubuntu screen(1) manpage on Ubuntu

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