/dev/null not writable

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Operating Systems Solaris /dev/null not writable
# 1  
Old 07-08-2011
/dev/null not writable


after a server (solaris 10) got rebooted, Im faced with the problem that in one of my zones (whole zone) /dev/null is only writeable for root
crw-r--r--   1 root     sys       13,  2 Jul  8 10:16 /dev/null

Unfortunatly chmod didnt help at this point and since its a productive system I dont really feel like removing and trying to recreate it, unless Im sure it will solve my problem.

Thanks for thoughts!
# 2  
Old 07-08-2011
Please clarify: "chmod didnt help at this point".
# 3  
Old 07-08-2011
you have to do this as root:
chmod 0666 /dev/null

# 4  
Old 07-08-2011
@Corona688: you can't do that in a non global zone as /dev is strictly mounted read only.
@bin-doph: did you try chmod'ing in the zoneroot dev directory from the global zone ?
# 5  
Old 07-11-2011
Hi everybody,

thanks for all the answers. I did try to chmod the device from the zone and from the global zone, almost without success. However, today I discovered that chmoding did work, but not for very long.

bash-3.00# chmod go+w /dev/null; ls -lah /dev/null
crw-rw-rw-   1 root     sys       13,  2 Jul 11 15:01 /dev/null
bash-3.00# ls -lah /dev/null
crw-r--r--   1 root     sys       13,  2 Jul 11 15:01 /dev/null

Between those two commands is a time-delta of me pasting the second command into the shell. I've tried to figure out what process does the permission-changes on the device, but so far without success. I hardly doubt there is a custom-script with the purpose of chmoding /dev/null, at least as far as I know...
# 6  
Old 07-11-2011
Neither the global zone nor the non global zone /dev/null change attempts will help.

As I already wrote, you need to modify the <zoneroot>/dev/null file from the global zone with zoneroot being the directory where your zone is installed.
# 7  
Old 07-12-2011
Originally Posted by jlliagre
Neither the global zone nor the non global zone /dev/null change attempts will help.

As I already wrote, you need to modify the <zoneroot>/dev/null file from the global zone with zoneroot being the directory where your zone is installed.
Sorry, maybe I was unclear on that point. I did the chmod on the /dev/null file of the zone from inside the global zone. The /dev/null file of the global zone itself got the right permissions and is a link to the pseudo device file. However, the file of the zone keeps getting its permissions changed back to the wrong state right away and I'm pretty positive that it's not something 'homemade' (like a users script), just havn't figured out yet where to search for the source.
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