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Old 12-27-2008, 12:29 PM   #1
kissaki
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Registered: Dec 2008
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redirect stdout to file produces blank file


I cannot redirect output from commands such as iptables, iptables-save, and ifconfig. For example, any of the following DOESN'T work ( as root ):
Code:
iptables > tmp
iptables-save > tmp
ifconfig > tmp
The file tmp is ALWAYS blank, that is, 0 bytes in size. Wackier things DO work, such as:
Code:
echo "`iptables-save`" > tmp
iptables-save | tee tmp
Other commands like:
Code:
ls > tmp
DO work as expected.

Note that this problem happens regardless if I log-in remotely via ssh or locally on the computer in question. I am clueless as to what is causing this. Any ideas?

The box is running 2.6.25-14.fc9.i686 and boots to runlevel 3. The modifications I've made to the box since installing the OS are things like compiling/installing latest OpenSSH,OpenSSL,httpd,BerkeleyDB,subversion,zlib etc -- nothing really out of the ordinary I'd say.
 
Old 12-27-2008, 12:48 PM   #2
pixellany
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Registered: Nov 2005
Location: Annapolis, MD
Distribution: Mint
Posts: 17,809

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If I am not mistaken, the redirect operator (>) redirects **anything** that would normally go to the screen as "stdout".

Example:
iptables does not exist on my machine..

"iptables" produces an error message (on the screen)
"iptables" > tmp same error message, nothing in the file
"iptables" 2> tmp nothing on the screen, error message in the file

"ifconfig > tmp" works as expected
 
Old 12-27-2008, 12:57 PM   #3
kissaki
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Registered: Dec 2008
Posts: 3

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Sorry, I should have stated:
Code:
iptables -L
in my original example. I also have /sbin in my path. Nonetheless, all of the following give me blank file output:
Code:
iptables -L > tmp
/sbin/iptables -L > tmp
iptables 2> tmp
/sbin/iptables 2> tmp
When I don't redirect the output to stdout is as expected.
 
Old 12-27-2008, 02:43 PM   #4
pixellany
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Location: Annapolis, MD
Distribution: Mint
Posts: 17,809

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I cannot duplicate this. I even installed iptables to test that specifically
 
Old 12-27-2008, 07:41 PM   #5
dquick1
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Registered: Dec 2008
Location: Geelong, Australia
Distribution: Fedora
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Double check you do not have a tmp directory in the directory you are working in?

Also, try this to redirect all output stdout, stderr etc to a file in another directory;

Code:
$iptables -L > /tmp/afile 2>&1

Also test to see if redirection will work to tmp in the directory you are in:

Code:
$ echo This is a line of text > tmp
or

Code:
$ echo This is a line of text > /tmp/afile.txt
Damien
 
Old 01-06-2009, 03:28 AM   #6
kissaki
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Registered: Dec 2008
Posts: 3

Original Poster
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Solved

Turns out it was SELinux preventing the write.
 
  


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