Cabrillo College Linux Classes

I really enjoy using the commands we learn in class on my computer at work (We use CentOS 5, same as Benji).

However, often times I'm not allowed to use these commands on my work computer. One example is the test we turned in yesterday. I'm not allowed to type "dumpe2fs /dev/sda |grep UUID". I get "dumpe2fs: Permission denied while trying to open /dev/sda"

I want to be able to ask our sysadmins at work to give me access to the appropriate things. But I am not quite sure what to ask them for. I want to sound like I know what I'm doing. Is it as simple as /dev/sda being a "file" I don't have access to?

Kayla,

It appears that you need write permissions to view superblock information on a device.
Here's an example:

[code]$ stat /dev/sda1
File: `/dev/sda1'
Size: 0 Blocks: 0 IO Block: 4096 block special file
Device: fh/15d Inode: 1196 Links: 1 Device type: 8,1
Access: (0640/brw-r-----) Uid: ( 0/ root) Gid: ( 6/ disk)
Access: 2008-12-10 18:25:18.220465702 -0800
Modify: 2008-12-10 10:36:36.067607980 -0800
Change: 2008-12-10 10:36:38.292140423 -0800 [/code]

Notice the access time is 18:25:18

[code] # sudo /sbin/dumpe2fs /dev/sda1 | grep UUID
dumpe2fs 1.40.8 (13-Mar-2008)
Filesystem UUID: 283294d4-365f-407f-bef8-1de88283f24f[/code]
[code]
$ stat /dev/sda1
File: `/dev/sda1'
Size: 0 Blocks: 0 IO Block: 4096 block special file
Device: fh/15d Inode: 1196 Links: 1 Device type: 8,1
Access: (0640/brw-r-----) Uid: ( 0/ root) Gid: ( 6/ disk)
Access: 2008-12-10 18:29:52.360122560 -0800
Modify: 2008-12-10 10:36:36.067607980 -0800
Change: 2008-12-10 10:36:38.292140423 -0800[/code]

Now the access times have changed to 18:29:52

I do a stat /dev/sda1 once more without running dumpe2fs:
[code]
$ stat /dev/sda1
File: `/dev/sda1'
Size: 0 Blocks: 0 IO Block: 4096 block special file
Device: fh/15d Inode: 1196 Links: 1 Device type: 8,1
Access: (0640/brw-r-----) Uid: ( 0/ root) Gid: ( 6/ disk)
Access: 2008-12-10 18:29:52.360122560 -0800
Modify: 2008-12-10 10:36:36.067607980 -0800
Change: 2008-12-10 10:36:38.292140423 -0800[/code]

The access time has not changed.

Kayla,

Could it be as simple as you need to be root?

Janis

[quote="janischaffin"]Kayla,

Could it be as simple as you need to be root?

Janis[/quote]

It is that simple. However...I'm not root, at work

dunno where you work, but assuming you don't have an IT job there, the question to ask is, "I am taking some Linux classes, are there any dev systems or a sandbox I can have root or maybe read only access to?"
Your admins will know what they can safely let you onto.

Check out pages 48-49 from our text. It deals with the /etc/sudoers file which can just give someone sudo powers or various levels of power. It seems to be a cool way of allowing certain commands from a user without giving them full root priveleges.

rK

Hi, Kayla.

Everyone answered your question better than this, but to address one part of your question explicitly: the files in the /dev directory are usually referred to as "devices".

BTW, I just picked up a cheapo Asus eee, and am looking to install a different version of linux on it.

I think dumpe2fs requires a formatted partition as an argument, as in 'dumpe2fs /dev/sda6', as opposed to plain vanilla /dev/sda.