Hi Experts,

I Have a query. In one of my server I just came to know that there was /dev/null file which is a not a character file. Its just a normal file. I know the command to create the character file (/dev/null) but what is the procedure. Like should i delete /dev/null and create or anything else. I have a doubt that we can't remove /dev/null right ?

Expected format:
crw-rw-rw- 1 root system 2, 2 Feb 25 15:13 /dev/null

Format in my server:
-rw-rw-rw- 1 root system 0 Feb 25 15:22 /dev/null

Thanks & Regards,
B. Jayadeava

Take my advice with a grain of salt since I'm not an AIX expert, but: Having a /dev/null that is not a character device could be a big problem, yes! Things might create huge files in it, expecting them to go into the bit bucket, but actually ending up on disk instead... Some memory mapping things might not work right... etc.

You're generally not supposed to delete anything in /dev/, no. But when things are messed up like this, don't know what else you're supposed to do.

See those numbers there, 2,2? They're what make /dev/null act like /dev/null and not be some other device. You give those to mknod when you create it, and also give it c to tell it it's a character device and not a block one.

rm /dev/null ; mknod -m 0666 /dev/null c 2 2 ; chown root:system /dev/null

Disclaimer: I have never used AIX. Everything I say below is based on the OP's statement that /dev/null is a regular file.

Although a less common scenario, there are times when using /dev/null for reading is useful. One example that comes to mind is with grep, to force its output to include filenames, you may explicitly list /dev/null in a find -exec predicate or an xargs invocation, to ensure that grep is never called with a single file argument. If /dev/null does not yield nothing but EOF ... woe.

Regards,
Alister

I think a more AIX way of recreating /dev/null on AIX is:

# rm /dev/null
# cfgmgr

Was/is the file really "/dev/null" or is it rather "/dev/nulll" (3 "l"s!) ? The latter is a residue of some typo in an AIX script, i believe. I have seen it at various customers even in newly installed systems, so i suppose some IBM script, maybe in the HACMP installation procedure, is the culprit.

See also this thread .

I hope this helps.

bakunin

No it was /dev/null only... N i tried rm /dev/null but din allow me to...

Real worls example of /dev/null usage with grep on HPUX systems, where grep lacks option to show filename where grep has matched the result.

find . -type f -exec grep "string" {} /dev/null \;
/root/test/string.txt:string