mjhjmtu

(TLDR Doug O'Neal's strace -f -e execve ./myprogram solved me problem)

I start a program on the command line. The executing program spawns processes. I would like to see or log the names of all processes spawned by the program.

Details

I've tried top with forest view V:

$ top -c -d 1

Only the parent program is briefly visible. I suspect the refresh rate is too slow to show the child processes.

I've tried to filter by COMMAND=myprogram but this most probably filters out the child processes.

The parent program spawns processes but I am not sure if top's forest view will show those new processes indented under the original process or independently. I'm not sure if a spawned process can be independent of the parent.

Update #1

I tried this answer with the sleep removed.

#!/bin/bash

mkdir -p "$HOME/ps_logs"

while true; do
 ps faux > "$HOME/ps_logs/ps_$(date +%Y-%m-%d_%H:%M:%S).log"
done

I filtered the output with:

grep -rnw './' -e 'myprogam'

All the files only contain myprogram. So how do I know if myprogram even spawns any processes?

I generally like using ps auxf because it visually shows the child processes under the parent visually:

$ ps auxf
...
root 637 0.0 0.0 110044 800 tty1 Ss+ 02:50 0:00 /sbin/agetty --noclear tty1 linux
root 983 0.0 0.1 404028 1136 ? Sl 02:50 0:11 /usr/sbin/VBoxService --pidfile /var/run/vboxadd-service.sh
root 1013 0.0 1.6 562416 16444 ? Ssl 02:50 0:03 /usr/bin/python -Es /usr/sbin/tuned -l -P
root 1015 0.0 0.4 105996 4108 ? Ss 02:50 0:00 /usr/sbin/sshd -D
root 20191 0.0 0.5 152116 5576 ? Ss 10:06 0:00 _ sshd: vagrant [priv]
vagrant 20193 0.0 0.2 152304 2872 ? S 10:06 0:00 _ sshd: vagrant@pts/0
vagrant 20194 0.0 0.2 115964 2644 pts/0 Ss 10:06 0:00 _ -bash
root 20232 0.0 0.2 201844 2956 pts/0 S 10:06 0:00 _ sudo -Es
root 20233 0.0 0.2 116208 2964 pts/0 S 10:06 0:00 _ /bin/bash
root 20510 0.0 0.1 151240 1932 pts/0 R+ 11:01 0:00 _ ps auxf
root 1115 0.0 0.2 91628 2192 ? Ss 02:50 0:00 /usr/libexec/postfix/master -w
postfix 1117 0.0 0.3 91800 4048 ? S 02:50 0:00 _ qmgr -l -t unix -u
postfix 20149 0.0 0.3 91776 4048 ? S 09:39 0:00 _ pickup -l -t unix -u
...

Additionally if you just want to view the list of PID + PGID you can use ps with these switches like so:

$ ps x -o "%p %r %c"
 PID PGID COMMAND
 1 1 systemd
 2 0 kthreadd
 3 0 ksoftirqd/0
 5 0 kworker/0:0H
 7 0 migration/0
 8 0 rcu_bh
 ...
 ...
 591 591 rngd
 594 594 systemd-logind
 596 596 smartd
 597 597 rsyslogd
 600 600 acpid
 616 616 abrtd
 617 617 abrt-watch-log
 630 630 atd
 637 637 agetty
 983 981 VBoxService
 1013 1013 tuned
 1015 1015 sshd
 1115 1115 master
 2426 2426 NetworkManager
 2439 2439 dhclient
 3123 3123 firewalld
 3828 0 kworker/u2:1