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User 102 is not listed , output of cat /etc/passwd

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
irc:x:39:39:ircd:/var/run/ircd:/bin/sh
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
libuuid:x:100:101::/var/lib/libuuid:/bin/sh
syslog:x:101:103::/home/syslog:/bin/false
messagebus:x:102:105::/var/run/dbus:/bin/false
colord:x:103:108:colord colour management daemon,,,:/var/lib/colord:/bin/false
usbmux:x:108:46:usbmux daemon,,,:/home/usbmux:/bin/false
pulse:x:110:119:PulseAudio daemon,,,:/var/run/pulse:/bin/false
rtkit:x:111:122:RealtimeKit,,,:/proc:/bin/false
hplip:x:113:7:HPLIP system user,,,:/var/run/hplip:/bin/false
saned:x:114:123::/home/saned:/bin/false
off220:x:1000:1000:off220,,,:/home/off220:/bin/bash
gdm:x:104:111:Gnome Display Manager:/var/lib/gdm:/bin/false   

but the output shows there's a user 102

    ps aux | grep -v `whoami`
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  24332  2248 ?        Ss   19:43   0:00 /sbin/init
root         2  0.0  0.0      0     0 ?        S    19:43   0:00 [kthreadd]
root         3  0.0  0.0      0     0 ?        S    19:43   0:00 [ksoftirqd/0]
root         5  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/u:0]
root         6  0.0  0.0      0     0 ?        S    19:43   0:00 [migration/0]
root         7  0.0  0.0      0     0 ?        S    19:43   0:00 [watchdog/0]
root         8  0.0  0.0      0     0 ?        S    19:43   0:00 [migration/1]
root        10  0.0  0.0      0     0 ?        S    19:43   0:00 [ksoftirqd/1]
root        11  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/0:1]
root        12  0.0  0.0      0     0 ?        S    19:43   0:00 [watchdog/1]
root        13  0.0  0.0      0     0 ?        S    19:43   0:00 [migration/2]
root        14  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/2:0]
root        15  0.0  0.0      0     0 ?        S    19:43   0:00 [ksoftirqd/2]
root        16  0.0  0.0      0     0 ?        S    19:43   0:00 [watchdog/2]
root        17  0.0  0.0      0     0 ?        S    19:43   0:00 [migration/3]
root        18  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/3:0]
root        19  0.0  0.0      0     0 ?        S    19:43   0:00 [ksoftirqd/3]
root        20  0.0  0.0      0     0 ?        S    19:43   0:00 [watchdog/3]
root        21  0.0  0.0      0     0 ?        S<   19:43   0:00 [cpuset]
root        22  0.0  0.0      0     0 ?        S<   19:43   0:00 [khelper]
root        23  0.0  0.0      0     0 ?        S    19:43   0:00 [kdevtmpfs]
root        24  0.0  0.0      0     0 ?        S<   19:43   0:00 [netns]
root        26  0.0  0.0      0     0 ?        S    19:43   0:00 [sync_supers]
root        27  0.0  0.0      0     0 ?        S    19:43   0:00 [bdi-default]
root        28  0.0  0.0      0     0 ?        S<   19:43   0:00 [kintegrityd]
root        29  0.0  0.0      0     0 ?        S<   19:43   0:00 [kblockd]
root        30  0.0  0.0      0     0 ?        S<   19:43   0:00 [ata_sff]
root        31  0.0  0.0      0     0 ?        S    19:43   0:00 [khubd]
root        32  0.0  0.0      0     0 ?        S<   19:43   0:00 [md]
root        34  0.0  0.0      0     0 ?        S    19:43   0:00 [khungtaskd]
root        35  0.0  0.0      0     0 ?        S    19:43   0:00 [kswapd0]
root        36  0.0  0.0      0     0 ?        SN   19:43   0:00 [ksmd]
root        37  0.0  0.0      0     0 ?        SN   19:43   0:00 [khugepaged]
root        38  0.0  0.0      0     0 ?        S    19:43   0:00 [fsnotify_mark]
root        39  0.0  0.0      0     0 ?        S    19:43   0:00 [ecryptfs-kthrea]
root        40  0.0  0.0      0     0 ?        S<   19:43   0:00 [crypto]
root        48  0.0  0.0      0     0 ?        S<   19:43   0:00 [kthrotld]
root        49  0.0  0.0      0     0 ?        S    19:43   0:00 [scsi_eh_0]
root        50  0.0  0.0      0     0 ?        S    19:43   0:00 [scsi_eh_1]
root        52  0.0  0.0      0     0 ?        S    19:43   0:00 [scsi_eh_2]
root        53  0.0  0.0      0     0 ?        S    19:43   0:00 [scsi_eh_3]
root        54  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/u:3]
root        75  0.0  0.0      0     0 ?        S<   19:43   0:00 [devfreq_wq]
root        76  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/0:2]
root        77  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/1:1]
root       273  0.0  0.0      0     0 ?        S    19:43   0:00 [jbd2/sda3-8]
root       274  0.0  0.0      0     0 ?        S<   19:43   0:00 [ext4-dio-unwrit]
root       354  0.0  0.0  17224   640 ?        S    19:43   0:00 upstart-udev-bridge --daemon
root       358  0.0  0.0  21828  1584 ?        Ss   19:43   0:00 /sbin/udevd --daemon
root       412  0.0  0.0  21784  1152 ?        S    19:43   0:00 /sbin/udevd --daemon
root       413  0.0  0.0  21732  1056 ?        S    19:43   0:00 /sbin/udevd --daemon
root       463  0.0  0.0      0     0 ?        S<   19:43   0:00 [kpsmoused]
root       570  0.0  0.0      0     0 ?        S<   19:43   0:00 [hd-audio0]
root       730  0.0  0.0  15180   400 ?        S    19:43   0:00 upstart-socket-bridge --daemon
root       748  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/3:2]
root       764  0.0  0.0      0     0 ?        S    19:43   0:00 [kworker/1:2]
root       788  0.0  0.0      0     0 ?        S    19:43   0:00 [jbd2/sda2-8]
root       789  0.0  0.0      0     0 ?        S<   19:43   0:00 [ext4-dio-unwrit]
root       801  0.0  0.0      0     0 ?        S    19:43   0:00 [jbd2/sda4-8]
root       802  0.0  0.0      0     0 ?        S<   19:43   0:00 [ext4-dio-unwrit]
102        828  0.0  0.0  24744  1884 ?        Ss   19:43   0:00 dbus-daemon --system --fork --activation=upstart
syslog     833  0.0  0.0 249464  1548 ?        Sl   19:43   0:00 rsyslogd -c5
root       865  0.0  0.0   7256   604 ?        Ss   19:43   0:00 dhclient3 -e IF_METRIC=100 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
root       980  0.0  0.0  17780   904 tty4     Ss+  19:43   0:00 /sbin/getty -8 38400 tty4
root       982  0.0  0.0  17780   908 tty5     Ss+  19:43   0:00 /sbin/getty -8 38400 tty5
root       994  0.0  0.0  17780   908 tty2     Ss+  19:43   0:00 /sbin/getty -8 38400 tty2
root       998  0.0  0.0  17780   904 tty3     Ss+  19:43   0:00 /sbin/getty -8 38400 tty3
root      1004  0.0  0.0  17780   900 tty6     Ss+  19:43   0:00 /sbin/getty -8 38400 tty6
root      1015  0.0  0.0 130900  3016 ?        Ssl  19:43   0:00 gdm-binary
root      1036  0.0  0.0 144868  4020 ?        Sl   19:43   0:00 /usr/lib/gdm/gdm-simple-slave --display-id /org/gnome/DisplayManager/Display1
daemon    1038  0.0  0.0  16900   376 ?        Ss   19:43   0:00 atd
root      1039  0.0  0.0  19104  1024 ?        Ss   19:43   0:00 cron
root      1130  2.6  0.3 145504 25804 tty7     Ss+  19:43   2:16 /usr/bin/Xorg :0 -background none -verbose -auth /var/run/gdm/auth-for-gdm-x1heKF/database -nolisten tcp vt7
root      1197  0.0  0.0      0     0 ?        S<   19:43   0:00 [iprt]
root      1236  0.5  0.0  20476  4832 ?        SNs  19:43   0:29 /usr/sbin/preload -s /var/lib/preload/preload.state
root      2555  0.0  0.0 2091628 3876 ?        Sl   19:43   0:00 /usr/sbin/console-kit-daemon --no-daemon
root      2622  0.0  0.0 200352  4032 ?        Sl   19:43   0:00 /usr/lib/policykit-1/polkitd --no-debug
root      2649  0.0  0.0 219860  4232 ?        Sl   19:43   0:00 /usr/lib/upower/upowerd
rtkit     2792  0.0  0.0 168864  1344 ?        SNl  19:43   0:00 /usr/lib/rtkit/rtkit-daemon
root      2805  0.0  0.0 121528  3700 ?        Sl   19:43   0:00 /usr/lib/accountsservice/accounts-daemon
root      2813  0.0  0.0      0     0 ?        S    19:43   0:00 [flush-8:0]
root      2816  0.0  0.0  17780   908 tty1     Ss+  19:43   0:00 /sbin/getty -8 38400 tty1
root      2819  0.0  0.0 180348  3992 ?        Sl   19:44   0:00 /usr/lib/gdm/gdm-session-worker
root      4081  0.0  0.0 193364  3856 ?        Sl   19:44   0:00 /usr/lib/udisks/udisks-daemon
root      4085  0.0  0.0  45512   804 ?        S    19:44   0:00 udisks-daemon: not polling any devices
root      4494  0.0  0.0      0     0 ?        S    20:30   0:00 [kworker/2:1]
root     11407  0.0  0.0 112888  3080 ?        Sl   19:58   0:00 /usr/sbin/system-tools-backends
root     11410  0.0  0.2  58884 19032 ?        S    19:58   0:00 /usr/bin/perl /usr/share/system-tools-backends-2.0/scripts/SystemToolsBackends.pl -m Platform
root     18649  0.2  1.2 569448 96392 ?        Sl   19:49   0:10 /usr/sbin/synaptic
root     18659  0.0  0.0  26548   784 ?        S    19:49   0:00 dbus-launch --autolaunch=51015c1973c6bd697d07027500000008 --binary-syntax --close-stderr
root     18660  0.0  0.0  23808   696 ?        Ss   19:49   0:00 //bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session

What is this user for? Why is it not listed in passwd? (sorry for formatting, can't get it to work)

share|improve this question

2 Answers 2

up vote 3 down vote accepted

if you look closesly over your /etc/password file, you'll notice that the user "messagebus" has a user I'd of 102. So what your ps shows is the numeric user id instead of the username, because it doesn't fit into the default column width of ps. Truncating a username is no option, since it would end up in confusion. But you can manually set a different width for the user column, e.g.

`ps ax -o pid,user:19,comm`

Now you should see the username turn to "messagebus". Btw. the command gives a hint to the right user: The running command is "dbus-daemon", the message bus daemon, that enables inter-process communication and runs under the system user "messagebus"!

share|improve this answer
    
Thanx, got it.. –  user73331 Aug 17 '12 at 16:40

The user is "messagebus" in your passwd file, here:

  messagebus:x:102:105::/var/run/dbus:/bin/false

The third option is the USERID, the fourth is the GROUPID.

Dbus is a messagin system for the applicatiopns to talk to each other.

You can read more about the dbus daemon and the messagebus here:

http://linux.die.net/man/1/dbus-daemon-1

share|improve this answer
    
yeah, man pages are always useful. I just got scared :) Thank you. –  user73331 Aug 17 '12 at 16:41

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