unexpected behavior while installing flock

vineet7kumar · 11-26-2008, 01:05 PM

I am using Ubuntu Hardy. I downloaded Flock tar.bz2 as user 'vineet'
I copied it to /opt
after copying and extracting there in opt the owner was changed to another user 'bhoot'.
Whereas where I actually downloaded there it's owner is 'vineet' only.
Why is the owner changed automatically?
Also I am unable to run flock-browser ...

Any help regarding this would be great.

Regards,
Vineet

jstephens84 · 11-26-2008, 01:12 PM

It could have changed owners due to extraction or just that it inherited the permissions from the /opt filesystem. Just guessing though. Did you give any extra parameters when extracting the file?

vineet7kumar · 11-27-2008, 09:18 AM

Hi,
Today I tried same thing with xmms tar.gz package . After extracting it made some other user '500' as it's owner ... What is this '500' username for ??
Is it an issue with tar command?
Any other ubuntu user please try it out .

Thanks and Regards,
Vineet

vineet7kumar · 11-27-2008, 09:23 AM

I don't have any username as '500' in the /etc/passwd file nor does any user have a userid 500 .

jstephens84 · 11-27-2008, 09:43 AM

post what you are typing in when untaring the package.

vineet7kumar · 11-28-2008, 09:59 AM

The package names are (in /opt)

flock_afc052961B81660-2.0.en-US.linux-i686.tar (owner root)

and

xmms-1.2.11.tar (owner root)

The command I am giving are

Code:

sudo tar -xvf flock_afc052961B81660-2.0.en-US.linux-i686.tar

and

Code:

sudo tar -xvf xmms-1.2.11.tar

after doing this the output of my ls -l command is as below

Code:

drwxr-xr-x 13 bhoot bhoot     4096 2008-10-07 21:41 flock
drwxrwxrwx 12   500   500     4096 2008-11-27 20:47 xmms-1.2.11
-rwxrwxrwx  1 root  root        65 2008-11-26 21:48 connect
-rw-------  1 root  root  37099520 2008-11-27 00:01 flock_afc052961B81660-2.0.en-US.linux-i686.tar
-rw-r--r--  1 root  root  15504764 2008-11-27 20:36 skype-debian_2.0.0.72-1_i386.deb
-rw-r--r--  1 root  root  17285120 2008-11-27 20:45 xmms-1.2.11.tar

do let me know if I should provide something more.

Thanks and regards,
Vineet

tredegar · 11-28-2008, 11:12 AM

tar was originally used for making tape archives, for backups.
It bundles up all the files in a directory and saves them in one big file: The tar file.
Along with the files themselves, it also saves data about who the files belonged to, and what group they were assigned to, and a lot of other useful stuff as well (time created, time modified etc.)

[This tar file can also be compressed.]

If you untar a tar file as the user root, then the directories and files will reappear, but with the original owner (UID) and group IDs (GIDs). These are just numbers.
If you untar a tar file as yourself, tar will automatically assign yourself as the owner of the untarred files, and the group assigned to the files will be your default group.

Because you untarred as root the original UID and GID will be assigned to the files.

Linux looks up these numbers in /etc/passwd and /etc/groups and then converts these numbers to username and groupname if it can. If it can't then it'll just show the number instead of a username or groupname.

So.... Someone with a username of bhoot on your machine has the same UID and GID numbers as the user who owned the original flock directory before it was tarred up and you downloaded it.
That's why the user & group are listed as bhoot for the flock directory.

But xmms-1.2.11 was tarred up by someone with a UID of 500 and a GID of 500.
You do not have any users or groups on your machine corresponding to these numbers, so linux cannot look them up, and it just prints the numbers.

Please see man chown for how to change the owner:group of files and man tar for the very many options for the tar command.

vineet7kumar · 11-28-2008, 01:52 PM

Wow ... very informative stuff... Thanks a Lot

Thanks & Regards,
Vineet

jstephens84 · 11-29-2008, 12:59 AM

Quote:

Originally Posted by tredegar

tar was originally used for making tape archives, for backups.
It bundles up all the files in a directory and saves them in one big file: The tar file.
Along with the files themselves, it also saves data about who the files belonged to, and what group they were assigned to, and a lot of other useful stuff as well (time created, time modified etc.)

[This tar file can also be compressed.]

If you untar a tar file as the user root, then the directories and files will reappear, but with the original owner (UID) and group IDs (GIDs). These are just numbers.
If you untar a tar file as yourself, tar will automatically assign yourself as the owner of the untarred files, and the group assigned to the files will be your default group.

Because you untarred as root the original UID and GID will be assigned to the files.

Linux looks up these numbers in /etc/passwd and /etc/groups and then converts these numbers to username and groupname if it can. If it can't then it'll just show the number instead of a username or groupname.

So.... Someone with a username of bhoot on your machine has the same UID and GID numbers as the user who owned the original flock directory before it was tarred up and you downloaded it.
That's why the user & group are listed as bhoot for the flock directory.

But xmms-1.2.11 was tarred up by someone with a UID of 500 and a GID of 500.
You do not have any users or groups on your machine corresponding to these numbers, so linux cannot look them up, and it just prints the numbers.

Please see man chown for how to change the owner:group of files and man tar for the very many options for the tar command.

Very nice explanation. I always thought it took the permissions straight from the directory.