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Arkaitz Jimenez
Asked: 2014-09-22 06:18:06 +0800 CST

Bash and background processes PGID and receiving signals

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My actual problem is that a process I run in an rcfile in docker as docker run container bash --rcfile rcfile remains attached to the bash session by sharing the PGID which means that when I Ctrl-C an unrelated command the process receives a SIGINT

So, inside the rcfile its just (nohup command &), when instead of using the rcfile I call it directly in the shell the PGID is different and Ctrl-C does not affect.

From there I deduced that for some reason, bash does not background processes the same while executing the rcfile.

Wrote a small test without docker where I see the PGID behavior.

RCFILE, sleep and bash share PGID

Cobain ~/tmp/testbash$ cat rcfile 
#!/bin/bash
(sleep 10 &)

Cobain ~/tmp/testbash$ bash --rcfile rcfile
arkaitzj@Cobain:~/tmp/testbash$ ps -o  "%p %r %y %x %c"
  PID  PGID TTY          TIME COMMAND
 2883  2883 pts/0    00:00:06 bash
27911 27911 pts/0    00:00:00 bash
27913 27911 pts/0    00:00:00 sleep
27914 27914 pts/0    00:00:00 ps

Command input in the shell, PGID differs

Cobain ~/tmp/testbash$ bash
Cobain ~/tmp/testbash$ ( sleep 10 &)
Cobain ~/tmp/testbash$  ps -o  "%p %r %y %x %c"
  PID  PGID TTY          TIME COMMAND
 2883  2883 pts/0    00:00:06 bash
27999 27999 pts/0    00:00:00 bash
28127 28126 pts/0    00:00:00 sleep
28132 28132 pts/0    00:00:00 ps

What I don't understand of this bash example though, is that in the rcfile case, when I ctrl-C it does not SIGINT the sleep process, when it is sharing the PGID

bash

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