Different PID with & and ps

Sarah_Student · 10-13-2009, 08:13 AM

Hi
I use Linux Suse Enterprise server 10.
I have installed mc on it.
While sending mc to background with mc & I receive a PID for example 7521 but when I use ps command to check the active processes, this PID (7521) is assigned to bash process and mc ID has changed to some thing more, for example 7525.
Can any one explain me the reason? For other processes that I have checked, the assigned PID is same.
Thanks in advance.

catkin · 10-13-2009, 11:04 AM

Please post the line you are using to send mc to background with mc &

Sarah_Student · 10-18-2009, 01:26 AM

I use these lines...
mc &
[1] 5704
ps
5502 pts/1 00:00:00 bash
5704 pts/1 00:00:00 bash
570B pts/1 00:00:00 mc
5710 pts/1 00:00:00 ps
[1]+ stopped mc

catkin · 10-18-2009, 06:42 AM

Intriguing. Here's equivalent from Slackware 13.0 (sorry -- don't know how to find version of mc; the -V option doesn't give it, grepping all the /var/log/packages files for /usr/bin/mc doesn't find it ...)

Code:

c:~$ mc &
[1] 7478
c:~$ ps
                         PID TTY          TIME CMD
 7116 pts/2    00:00:00 bash
 7478 pts/2    00:00:00 mc
 7481 pts/2    00:00:00 ps

[1]+  Stopped                 mc
c:~$ type mc
mc is hashed (/usr/bin/mc)
c:~$ file /usr/bin/mc
/usr/bin/mc: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), stripped

itz2000 · 10-18-2009, 01:15 PM

Code:

root@Peanut:/home/donkey# vim &
[1] 3404
root@Peanut:/home/donkey# ps
  PID TTY          TIME CMD
 3373 pts/0    00:00:00 bash
 3404 pts/0    00:00:00 vim That's how it should be
 3405 pts/0    00:00:00 ps

[1]+  Stopped                 vim
root@Peanut:/home/donkey# ps
  PID TTY          TIME CMD
 3373 pts/0    00:00:00 bash
 3404 pts/0    00:00:00 vim
 3406 pts/0    00:00:00 ps
root@Peanut:/home/donkey# ps
  PID TTY          TIME CMD
 3373 pts/0    00:00:00 bash
 3404 pts/0    00:00:00 vim
 3407 pts/0    00:00:00 ps
root@Peanut:/home/donkey# kill %1

[1]+  Stopped                 vim

The reason is simple, you actually don't run mc, but running bash that run mc.
do the commands :

Code:

export
ls -l `which mc`
strace mc

and post the results here so we can point out why it happened

Sarah_Student · 10-19-2009, 01:01 AM

My output for vim is same as yours.
I think because mc is visual view of shell, first, shell should run and then mc.
Output of the commands you have written is very long.
Should I send it anyway?

itz2000 · 10-19-2009, 04:49 PM

Quote:

Originally Posted by Sarah_Student

My output for vim is same as yours.
I think because mc is visual view of shell, first, shell should run and then mc.
Output of the commands you have written is very long.
Should I send it anyway?

yeah why not, so we can learn about this a little more and teach some stuff...