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UGU: Unix Guru Universe - Unix Tip #4422- April 20, 2025
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 Unix Tip #4422- April 20, 2025
 
TRIMMING THE LOG  
  
  
Various unix processes can  
produce fast growing logs that  
sometimes need to be trimmed  
instead of deleted, for reference  
or troubleshooting. And you  
likely have no desire to edit the  
files. Here is a handy ksh  
script that will quickly trim  
the log so it keeps recent  
information and lets you keep as  
many lines as you think you might  
need. I call it trimlog:  
  
#! /bin/sh  
# trimlog  
filesize=`cat $1|wc -l`  
trim=`expr $filesize - $2`  
if [ $trim -gt 0 ]  
then  
sed "1,$trim d" $1 > /tmp/$1  
mv /tmp/$1 $1  
echo $1 trimmed by $trim lines  
fi  
  
Use it by feeding in the name of  
the log you want to trim followed  
by the number of lines you want to  
keep:  
  
# trimlog oracle_listener.log 10000  
  
  
Of course you can't use it in  
the /tmp directory. There are  
probably newer and more efficient  
ways to do this, but this works.  
 NOTE: All tips provided are USE AT YOUR OWN RISK. Tips are submitted
by various unix admins around the globe. UGU suggest you read and
test each tip in a non-volitile environment before placing into
production.
  
LAST 5 TIPS
 4421
 - FOLDING IN LINUX
 4420
 - THE NEXT UID
 4419
 - TRANSFERRING MULTIBYTE FILES
 4418
 - LOGGING MAKES
 4417
 - ALIAS YOUR CONNECTIVITY
 
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