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Need to rid of some output

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afflictedd2
 PostPosted: Thu Dec 11, 2008 2:08 pm   

Joined: Wed Nov 26, 2008 7:43 pm
Posts: 50
Location: Texas
Hi everyone,

How do I get rid of the output generated by the grep '^ELF' statement?

Code:
#!/bin/bash
if file -b $i | grep "^ELF"; then 
   echo "$i is a library";
else    
   echo "not a library";
fi
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DarthWavy
 PostPosted: Fri Dec 12, 2008 3:07 am   
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Joined: Thu Oct 11, 2007 7:12 am
Posts: 265
Location: London - UK
Here are a couple of ways.
Firstly recent versions of grep have a '-q' switch which suppresses output, perfect for if statements.

Code:
if file -b $i | grep -q "^ELF"


or just redirect the output

Code:
if file -b $i | grep "^ELF" >/dev/null
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fredrik.eriksson
 PostPosted: Fri Dec 12, 2008 7:28 am   

Joined: Mon Nov 17, 2008 7:25 am
Posts: 221
or do it the long way around :P
Code:
file -b $i | grep "^ELF" > /dev/null
if [ $? -eq 0 ]; then

fi


Dunno how well if likes when you need to redirect stderr at the same time, i've done this way sometimes for reasons I cannot remember now :P

Best regards
Fredrik Eriksson
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afflictedd2
 PostPosted: Fri Dec 12, 2008 11:02 am   

Joined: Wed Nov 26, 2008 7:43 pm
Posts: 50
Location: Texas
neither worked X\
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fredrik.eriksson
 PostPosted: Fri Dec 12, 2008 9:31 pm   

Joined: Mon Nov 17, 2008 7:25 am
Posts: 221
Code:
file -b $i | grep "^ELF" 2>&1 /dev/null
if [ $? -eq 0 ]; then

fi


That should do the trick, if it's stderr that is... i'm quite drunk atm so i donot guarantee that quality of this :P

Best regards
Fredrik Eriksson
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afflictedd2
 PostPosted: Sat Dec 13, 2008 7:53 am   

Joined: Wed Nov 26, 2008 7:43 pm
Posts: 50
Location: Texas
godammit you're always drunk :lol:
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