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if string is there then do nothing

Posted on 2013-01-11
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Last Modified: 2013-01-15
I am trying to create an if statement that searches for the string and if its there don't do anything my script is still writing into the file I want it to not write if the string is there and if its not there then write the string into the file this is what I have.


if grep -q "string" /etc/syslog.conf
then
sed -i -e '/^authpriv.info/ a\
authpriv.none\t\t\t\t\t\t\t/var/log/secure' /etc/syslog.conf
else
     if grep -q "string" /etc/syslog.conf
     then
     echo "authprive.none exists"

     fi
fi
0
Comment
Question by:atom_jelly
7 Comments
 
LVL 68

Assisted Solution

by:woolmilkporc
woolmilkporc earned 336 total points
ID: 38768661
Use

if ! grep ...

in the first line.
0
 
LVL 7

Assisted Solution

by:amitnepal
amitnepal earned 332 total points
ID: 38768707
grep -q "string" /etc/syslog.conf
if [ $? -eq 0 ];then
      sed -i -e '/^authpriv.info/ a\
      authpriv.none\t\t\t\t\t\t\t/var/log/secure' /etc/syslog.conf
else
      grep -q "string" /etc/syslog.conf
      if [ $? -eq 0 ];then
            echo "authpriv.none exists"
      fi
fi
0
 
LVL 38

Assisted Solution

by:Gerwin Jansen, EE MVE
Gerwin Jansen, EE MVE earned 664 total points
ID: 38769015
You could try writing your script in 'pseudo' code first and then replace 'pseudo' code with real code. Like this:

if 'string is not there'
then 'do nothing'
else 'write string to file'

would translate into:

if ! grep -q "string" /etc/syslog.conf
then
  echo "authprive.none exists"
else
  sed -i -e '/^authpriv.info/ a\
  authpriv.none\t\t\t\t\t\t\t/var/log/secure' /etc/syslog.conf
fi
0
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LVL 51

Assisted Solution

by:ahoffmann
ahoffmann earned 668 total points
ID: 38769562
grep -q 'string' || echo writing into the > file
0
 
LVL 38

Assisted Solution

by:Gerwin Jansen, EE MVE
Gerwin Jansen, EE MVE earned 664 total points
ID: 38769586
@ahoffmann:
grep -q 'string' somefile || echo writing into the > file
0
 
LVL 51

Accepted Solution

by:
ahoffmann earned 668 total points
ID: 38769597
(only if you want it to be completed in measurable time :-)
thanks
0
 

Author Closing Comment

by:atom_jelly
ID: 38777957
Thank you all.
0

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