97

Resolved before asked: cat /proc/1111/status | grep PPid

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  • faster: grep PPid status |cut -f2 like in time(for((i=0;i<1000;i++));do grep PPid status |cut -f2 >/dev/null;done); wonder if there is something even faster? – Aquarius Power Aug 9 '14 at 23:55
  • 1
    @AquariusPower Since you ask, fgrep is faster than grep. fgrep PPid status |cut -f2 – jbo5112 Feb 18 '16 at 22:46
  • sed is way faster than grep and cut: sed -rn '/PPid/ s/^.*:\s+// p' < status – Marian Apr 25 '17 at 23:15

10 Answers 10

113

Command line:

ps -o ppid= -p 1111

Function:

ppid () { ps -p ${1:-$$} -o ppid=; }

Alias (a function is preferable):

alias ppid='ps -o ppid= -p'

Script:

#!/bin/sh
pid=$1
if [ -z $pid ]
then
    read -p "PID: " pid
fi
ps -p ${pid:-$$} -o ppid=

If no PID is supplied to the function or the script, they default to show the PPID of the current process.

To use the alias, a PID must be supplied.

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  • The = sign is not necessary, at least on OS X 10.8.2. – jtbandes Jan 9 '13 at 19:04
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    @jtbandes: The equal sign as used here suppresses the output of the header line (Linux and OS X). – Paused until further notice. Jan 9 '13 at 21:08
15

This is one of those things I learn, forget, relearn, repeat. But it's useful. The pstree command's ‘s’ flag shows a tree with a leaf at N:

pstree -sA $(pgrep badblocks)
systemd---sudo---mkfs.ext4---badblocks
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  • What about ps f? – Alex78191 Apr 3 at 18:32
12

Parent pid is in shell variable PPID, so

echo $PPID
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  • 1
    Yes, but 1. I want parent pid of other process, 2. I want to be able to traverse all ancestors to init. – Vi. Sep 24 '12 at 12:37
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    On the other hand, using $PPID did just solve the problem I had which Google suggested this page as an answer to. – Paul Whittaker Sep 24 '12 at 15:58
12

To print parent ids (PPID) of all the processes, use this command:

ps j

For the single process, just pass the PID, like: ps j 1234.

To extract only the value, filter output by awk, like:

ps j | awk 'NR>1 {print $3}' # BSD ps
ps j | awk 'NR>1 {print $1}' # GNU ps

To list PIDs of all parents, use pstree (install it if you don't have it):

$ pstree -sg 1234
systemd(1)───sshd(1036)───bash(2383)───pstree(3007)

To get parent PID of the current process, use echo $$.

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  • 1
    pstree is the nicest one I've seen here. – sudo Sep 8 '17 at 0:33
  • ps j is great because it's available on many distros and is easily composable – Connor McCormick Jul 22 '19 at 20:58
6

Read /proc/$PID/status. Can be easily scripted:

#!/bin/sh
P=$1
if [ -z "$P" ]; then
    read P
fi
cat /proc/"$P"/status | grep PPid: | grep -o "[0-9]*"
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  • 2
    grep '^PPid:' /proc/$1/status | grep -o '[0-9]*' is all you need. (It is very uncommon for Unix tools to do the if [ -z ]; then read thing.) – user1686 Jun 8 '10 at 11:12
  • @grawity It helps do do things like echo $$ | ppid | ppid | ppid – Vi. Jun 9 '10 at 13:04
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    UUOC useless use of cat – Felipe Alvarez Nov 25 '14 at 0:26
  • @FelipeAlvarez, My hands are not used to type < /some/file grep | grep | .... – Vi. Nov 25 '14 at 0:29
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    What about grep /some/file – Felipe Alvarez Nov 25 '14 at 0:35
4

On Linux:

ps hoppid $thatprocess
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2

Run top with whatever options you want, like -u username and -p PID.

And while top is working press f, it shows a list of options you want to display in top output, and the displayed parameters will be shown in CAPITAL letters and the parameters which or not displaying will be shown in small letters.

So by entering the letter before the parameter you can enable or disable it. For parent process ID you have to enter b and then press Enter, it'll display the PPID in top output.

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  • 1
    It is to be used non-interactively. I already know that in htop you can configure PPID column. – Vi. Nov 23 '12 at 13:49
2
$ ps -p $(ps -p $(echo $$) -o ppid=) -o comm=
    tmux

A little bit more complex example that checks the command of a parent that started current process Change comm= to cmd= to see full command

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  • Useless use of echo? ;) – bobbogo Oct 12 '17 at 10:21
  • It is actually required on some terminals. To be honest I don't remember exactly but it actually solved a problem. :D – sebastian_t Oct 13 '17 at 7:08
1

Here is a quick solution that should also work:

ps $$
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0

all parent processes of a pid

I came here when I was trying to find "all parent processes of a pid". I ended up making my own recursive function to do it.

pid_lineage.sh

#!/bin/bash -eu

main(){
  ps -p ${1:-$$} -h -o pid,ppid,args | \
    (
      read pid ppid args
      echo -e "$pid\t$args"
      [[ $pid -gt 1 ]] && main $ppid
    )
}

main "$@"
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