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Old 08-08-2012, 02:10 PM   #1
micronemo
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Insert lines on top of a text file


hello, i must insert output of echo "$(date +%Y%m%d%H%M%S) Inizio backup" on top of text file pippo.log . can you help me with awk or sed command. thanks very very much
 
Old 08-08-2012, 02:45 PM   #2
Tinkster
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Hi, welcome to LQ!

How about something like this?
Code:
(echo Blah && cat backup) > backup.tmp && mv backup.tmp backup

Cheers,
Tink
 
Old 08-08-2012, 03:23 PM   #3
micronemo
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thanks, but can't create temporary file , i must do it with i single command.
i try with this but i don't know how complete this:
echo "$(date +%Y%m%d%H%M%S) Inizio backup" | sed -e ' ????1i' /root/pippo.log
 
Old 08-08-2012, 05:40 PM   #4
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Code:
sed -i "1i""$(echo \"$(date +%Y%m%d%H%M%S) Inizio backup\")" /root/pippo.log

Last edited by Tinkster; 08-08-2012 at 06:09 PM.
 
Old 08-08-2012, 06:02 PM   #5
micronemo
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thank very very much
work very well
 
Old 08-08-2012, 06:09 PM   #6
Tinkster
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Welcome ... sorry about the duplicated echo :) .. I'm sure you got
that sorted yourself, though ;)
 
Old 08-09-2012, 04:25 AM   #7
micronemo
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there is a little problrem if the file "pippo.log" is empty don't add the line in sed command
 
Old 08-09-2012, 04:10 PM   #8
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Can you please rephrase that? I don't understand what a) the problem and b) the
desired result is ... :)
 
Old 08-09-2012, 04:22 PM   #9
micronemo
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if pippo.log contains one or more lines your command work very well but if pippo.log is empty your command don't work.
i must have a command that work with empty file and not empty file
thanks
 
Old 08-09-2012, 04:39 PM   #10
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You won't be able to do this with a sed one-liner I'm afraid, sed operates on lines.
Write a wrapper script.

Code:
if [ `cat /root/pippo.log 2>/dev/null |wc -l` -eq 0 ]; then
  echo "" > /root/pippo.log
fi
sed -i "1i""$(echo \"$(date +%Y%m%d%H%M%S) Inizio backup\")" /root/pippo.log

Last edited by Tinkster; 08-09-2012 at 04:42 PM. Reason: minor amendment :)
 
Old 08-09-2012, 05:14 PM   #11
micronemo
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thanks
 
  


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