Do I need user 1000, and can I replace it?

Question

On my computer running Mythbuntu, I'm having a problem where some important processes are being run by a user called 1000.

$ ps -aux | grep myth
Warning: bad ps syntax, perhaps a bogus '-'? See http://procps.sf.net/faq.html
avahi     1126  0.0  0.0   3568  1536 ?        S    Jul08   0:02 avahi-daemon: running [mythbuntu.local]
mythtv    1863  0.0  0.8 323960 36096 ?        Sl   Jul08   3:38 /usr/bin/mythbackend --syslog local7 --user mythtv
1000      2278  0.0  0.0   4060   204 ?        Ss   Jul08   0:01 /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session /usr/share/mythbuntu/session.sh
1000      2281  0.0  0.0   3920   740 ?        S    Jul08   0:00 /usr/bin/dbus-launch --exit-with-session /usr/share/mythbuntu/session.sh
1000      2336  0.0  0.0   2216   592 ?        S    Jul08   0:00 /bin/sh /usr/bin/mythfrontend --service
root      8365  0.0  0.0  10104  3420 ?        Ss   17:40   0:00 sshd: mythbuntu [priv]
1000      8548  0.1  0.0  10252  1772 ?        S    17:40   0:00 sshd: mythbuntu@notty
1000      8624  0.0  0.0   4132   836 pts/3    S+   17:41   0:00 grep --color=auto myth
1000     12749  1.7  6.9 618604 288348 ?       Sl   Jul11 148:53 /usr/bin/mythfrontend.real --syslog local7

This seems to be causing other problems with permissions, because processes run by this user can't seem to access commands I need to run from within MythTV and other processes owned by 1000.

So far as I know, there's only one user on my system that I created, called mythbuntu, and my intention was that user run everything. I don't know what this 1000 user is or where it came from.

$ grep 1000 /etc/passwd
mythbuntu:x:1000:1000:mythbuntu,,,:/home/mythbuntu:/bin/bash

Is this 1000 user important or a default in some way? Or is there a way I can have this 1000"user essentially removed and anything attributed to that user overtaken by the mythbuntu user?

Note: this is an extension of an issue I'm trying to resolve on the Ubuntu Forums.

Answer 1

User ID 1000 is Mythubuntu, your user (notice that the grep command was ran by that user when you executed it). The apparent phenomenon is that ps does not report user names if they are longer than 8 (eight) characters, and subtitutes it with the user id.

(Off: The proper syntax is ps aux, not ps -aux (no need for the hyphen). Note the output throws an error on it too.)

Edit

To show an example:

whisperity@Aspire-5315:/tmp$ ls -l | grep DaveMG
drwxr-xr-x  2 whisperity whisperity     4096 2012-07-18 12:20 DaveMG

Clearly, my user has rights to write the folder. I can write into it:

whisperity@Aspire-5315:/tmp$ echo "hello Dave" > DaveMG/foobar
whisperity@Aspire-5315:/tmp$ ls -l DaveMG
total 4
-rw-r--r-- 1 whisperity whisperity 11 2012-07-18 12:21 foobar

When I look at the process list (let's say I hexdump the file), it will show something like this:

whisperity@Aspire-5315:/tmp/DaveMG$ ps aux | grep hexdump
1000     13893  0.8  0.0   3912   508 pts/2    S+   12:24   0:00 hexdump /tmp/somebigfile
1000     13895  0.0  0.0   4156   860 pts/3    S+   12:24   0:00 grep --color=auto hexdump

Because whisperity is more than eight characters (it's nine characters long), ps shows my user's ID.

whisperity@Aspire-5315:/tmp/DaveMG$ cat /etc/passwd | grep 1000
whisperity:x:1000:1000:Whisperity,,,:/home/whisperity:/bin/bash