How to list only non-<defunct> processes?

Question

Is there a combination of command-line options for ps or pgrep or some other relatively direct way to determine if a particular process name is actually running (available for normal use)..

By "running", I mean to specifically exclude processes which are <defunct> or any other non-running processes (eg. zombies :)...

This sample script shows an example of <defunct> items:

#!/bin/bash   ubuntu 10.04

  pgrep ^gnuserv$
# 25591
# 25599
# 27330

  ps $(pgrep ^gnuserv$)  # command ammended as per pilcrow's good suggestion
#   PID TTY      STAT   TIME COMMAND
# 25591 ?        Zs     0:00 [gnuserv] <defunct>
# 25599 ?        Zs     0:00 [gnuserv] <defunct>
# 27330 pts/2    S+     0:00 gnuserv

---

I could further sed the output, but I think/hope there's a more direct way...

Answer 1

In your comment you clarify:

I'm actually looking for a single step option to ps or pgrep (or similar) which only outputs "active" processes...

I'm afraid you're out of luck with current ps/pgrep implementations.

Post filtering like this relies on a full understanding of the intial output, which I don't have...

But you can get that understanding and, better yet, control that output as desired. Try something like this:

function pgrep_live {
  pids=$(pgrep "$1");
  [ "$pids" ] || return;
  ps -o s= -o pid= $pids | sed -n 's/^[^ZT][[:space:]]\+//p';
}

That will return the pids for any pgrep'd processes matching your input string, which processes are "available for normal use," that is, neither dead+unreaped (Z) nor stopped (T).

Answer 2

you can try with the -v option of grep which negate the regular expression like this:

for p in $(pgrep ^gnuserv$) ;do ps x |grep "^\s*$p" | grep -v \<defunct\> ;done

Answer 3

## bash

## function to check if a process is alive and running:

_isRunning() {
    ps -o comm= -C "$1" 2>/dev/null | grep -x "$1" >/dev/null 2>&1
}

## example 1: checking if "gedit" is running

if _isRunning gedit; then
    echo "gedit is running"
else
    echo "gedit is not running"
fi

## example 2: start lxpanel if it is not there

if ! _isRunning lxpanel; then
    lxpanel &
fi

## or

_isRunning lxpanel || (lxpanel &)

---

Note: pgrep -x lxpanel or pidof lxpanel still reports that lxpanel is running even when it is defunct (zombie); so to get alive-and-running process, we need to use ps and grep

Answer 4

List processes whose command lines match a string:

livepgrep(){ ps o state=,pid=,command=|sed -E -n "/ sed -E -n/d;/^[^ZT] +[0-9]+ .*$@/p"; }
              ^ ^   ^      ^      ^      ^  ^         ^            ^      ^        ^
              | |   |      |      |      |  |         |            |      |        |
processes ----+ |   |      |      |      |  |         |            |      |        |
output format --+   |      |      |      |  |         |            |      |        |
process state ------+      |      |      |  |         |            |      |        |
pid -----------------------+      |      |  |         |            |      |        |
full command line ----------------+      |  |         |            |      |        |
sed as the filter -----------------------+  |         |            |      |        |
use extended regex -------------------------+         |            |      |        |
exclude sed from search results ----------------------+            |      |        |
state != Z (zombie, defunct) != T (stopped) -----------------------+      |        |
pid ----------------------------------------------------------------------+        |
string to search in the command line ----------------------------------------------+

Examples:

$ livepgrep tint2
S   493 tint2
$ livepgrep python
S   525 /usr/bin/python /bin/udiskie -C -F -s
S   580 python2 /home/xxx/bin/twmcpuram