-P ppid,...
              Only match processes whose parent process ID is listed.

OK, but you forgot one:

       -Z ppid,...
              Only match processes whose process ID is listed.

That way one could do
$ pkill  -Z  $!
instead of
$  kill 2>&- $!
if one wanted.
(-Z is just an arbitrary choice.)

Hello,
  I'm confused what you are trying to get pkill to do.
What are you trying to do here and doesn't /bin/kill do this function?

 - Craig

CS>   I'm confused what you are trying to get pkill to do.
CS> What are you trying to do here and doesn't /bin/kill do this function?

Pkill allows one to cautiously only kill any existing processes that
match the given specifications.

OK, here's the specification: process number 12345. Wait! There's no way
to tell pkill that.

So we end up having to use real kill(1), and having to deal with
* Error messages in case the process doesn't exist.
* Error shell $? return value in case process doesn't exist.
Instead of being able to use the uniform pkill interface.

Could you use -F to do that?

  $ pgrep -F file_with_pids

OK. Then at man pkill
       -F, --pidfile file
              Read PID's from file.  This option is perhaps more useful for pkill than pgrep.

add example

$ sleep 1111&
[2] 40473
$ pkill -F /dev/stdin <<< $!
[2]+  Terminated              sleep 1111

as the workaround allowing pkill to work directly with process numbers.

We believe that the bug you reported is fixed in the latest version of
procps, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 612146@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Craig Small <csmall@debian.org> (supplier of updated procps package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Thu, 29 Jan 2026 21:34:30 +1100
Source: procps
Binary: libproc2-1 libproc2-1-dbgsym libproc2-dev procps procps-dbgsym
Architecture: source amd64
Version: 2:4.0.6-1
Distribution: experimental
Urgency: medium
Maintainer: Craig Small <csmall@debian.org>
Changed-By: Craig Small <csmall@debian.org>
Description:
 libproc2-1 - library for accessing process information from /proc
 libproc2-dev - library for accessing process information from /proc
 procps     - /proc file system utilities
Closes: 469156 612146 883638 925437 926361 959375 978989 1068904 1080335 1108549
Changes:
 procps (2:4.0.6-1) experimental; urgency=medium
 .
   * New upstream version
     library and w: Don't check for sd_booted Closes: #1108549
     pgrep: Match on process ID Closes: #612146
     pgrep: Add --quiet option
     pmap: add -k option to print raw names from kernel
     ps.1: cols and collums alias width option Closes: #926361
     ps.1: Add format equivalents Closes: #925437
     slabtop: Increase column width Closes: #959375
     sysctl: Use options after --system  Closes: #978989
     w: Add terminal mode to show all terminal sessions
     w: Use process TTY as backup for user TTY Closes: #1080335
     w: Use correct return value for sd_get_sessions Closes: #1068904
     watch: Add --follow option Closes: #469156
     watch: 256 color support
     watch.1: Warn about -d permanent option Closes: #883638
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