dbus-daemon ... and its unix account

English Applications
1

Colleagues. I have a web tool that, amongst other things, gives a summary of the unix processes.

I see one entry that has the following:

> ps -ef | grep messa
message+ 772 1 0 09:26 ? 00:00:00 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation

The tool assumes that either the unix account exists locally, or it is defined to LDAP (which I do not have) and then does a ’ finger’ on the account.

> finger ruud
Login: ruud Name: Ruud xxxxxxxxxxxxxxxxxxxxxxxx
Directory: /home/ruud Shell: /bin/bash
On since Mon Feb 15 09:37 (CET) on pts/0 (messages off) from :0
No Mail.
No Plan.

> finger message+
finger: message+: no such user.

So, I have 2 questions:

  1. I thought that if something ran under a unix account (UID), then that account had to exist - somewhere
  2. Why was the name message+ chosen, and what is the significance of the +

Thx in advance for your help and input … Ruud

2

I do not know exactly why this is shown as message+. On my (13.1) system:

henk@boven:~> ps -ef | grep dbus-daemon
message+   577     1  0 09:34 ?        00:00:01 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
henk      1897     1  0 09:34 ?        00:00:01 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
henk      8478  8324  0 13:55 pts/1    00:00:00 grep --color=auto dbus-daemon
henk@boven:~>

and

henk@boven:~> ps -ef n | grep dbus-daemon
     498   577     1  0 09:34 ?        Ss     0:01 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
     500  1897     1  0 09:34 ?        Ss     0:01 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
     500  8486  8324  0 13:56 pts/1    S+     0:00 grep --color=auto dbus-daemon
henk@boven:~>

and

henk@boven:~> grep 498 /etc/passwd
avahi-autoipd:x:499:498:User for Avahi IPv4LL:/var/lib/avahi-autoipd:/bin/false
messagebus:x:498:494:User for D-Bus:/run/dbus:/bin/false
henk@boven:~>

Thus it seems that the real username for the UID is messagebus. Maybe it is shortened by the ps command for reasons of space.

3

Thx Henk, nice bit of investigative work. I repeated what you did:

mqm@suseleap421:~/vmq> ps -ef n | grep dbus-daemon
499 772 1 0 10:51 ? Ss 0:00 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
485 1232 1 0 10:51 ? Ss 0:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
1000 1472 1 0 10:52 ? Ss 0:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 15 --session
482 7371 31703 0 15:56 pts/0 S+ 0:00 grep --color=auto dbus-daemon
0 24831 1 0 14:50 ? Ss 0:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session

mqm@suseleap421:~/vmq> cat /etc/passwd | grep 499
messagebus:x:499:499:User for D-Bus:/var/run/dbus:/bin/false

I will alter the script and use the ‘n’ option of ps.

Cheers … Ruud

4

Strange thing is that I found the following in the man page:

If the length of the username is greater than the length of the display column, the numeric user ID is displayed instead.

Quod non?!?!

5

Looks like a ‘typo’ … or at least a mismatch between reality and ’ the manual’ … :wink: