user crontab, needs root privileges ?!

hen770 · 03-20-2011, 07:08 AM

Hi,

i know the subject is hard to understand but i did my best with it.

the problem:

i have 2 HDs on my Ubuntu OS, the first is 1TB and the other is 500GB, i want to do a backup with rsync from my 1TB HDs (in with the Ubuntu is on it) to the 500GB.

on the 500GB i have a partition called Backup.

what i did:

i have created a user crontab that dose two things:
1. mount the Backup partition from the 500GB to a folder called /~/Backup on my home directory which is on the 1TB HD.

2. i wrote the proper rsync command for the backup to go.

that is my crontab, ('hanan' is the username):

Code:

SHELL=/bin/bash
MAILTO=hanan
33 3    * * * /bin/mount /dev/sdb2
34 3    * * * /usr/bin/rsync -r -t -v --progress --delete --size-only /home/hanan/Programs/Stuff/Printers/ /home/hanan/Backup/

the problem:

when the time for the crontab comes it mounts the Backup partition to the right location on the user's home directory, but it can't do the second step because it needs root privileges in order to write on the mounted HD.

i have tried that manually and still i can't copy any file to the mounted HD unless i do it with the sudo command.

am i missing something ?

i want to that via the CLI and cron just for the study experience.

thanks.

hen770 · 03-20-2011, 07:42 AM

here is some more info about it:

i have an entry in my /etc/fstab file like that:

/dev/sdb2 ~/Backup ext4 defaults,noauto,users 0 0

i am able to mount it without the sudo command, but i can't write to the mounted HD.

that is:
before i mount the HD, the folder Backup on my home folder had the following permissions:
Code:
drwxr-xr-x 3 hanan hanan 4096 2011-03-20 03:23 Backup
and after i mount it (via the crontab, or manually without sudo), it become like that:
Code:
drwxr-xr-x 2 root root 4096 2011-03-20 03:21 Backup
here i think the problem is hide, why it is the directory become the root owner ?!

ongte · 03-20-2011, 08:09 AM

You should change the owner after you've mounted the partition. All you need to do now is mount the partition & run chown to change the owner to yourself.

Quote:

$ sudo chown hanan.hanan Backup

You only need to do this once & it should be working after that.

Explanation:
Since you partition was formated by root (using sudo), the filesystem that was created is naturally also owned by root. You have to mount the partition & manually change the owner. This goes for all filesystems that understand UNIX permissions (ext2/3/4,reiserfs,btrfs). This does not apply to non-UNIX filesystems like vfat/ntfs, where the owner/permission is specified during mount, udev or fstab.

hen770 · 03-21-2011, 03:15 AM

Thank you !

i have 2 options now, what is the best method:

1. to change the permissions to 777 and still leave it by the owner of root.
2. change the owner to my name.

.

ongte · 03-21-2011, 09:08 AM

If you are the only user on this computer, there's no reason not to change the owner. If not, you can always change both.