"sed" to check file size & echo " " to destination file

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# 1  
Old 11-13-2007
"sed" to check file size & echo " " to destination file


I've modified the syslogd source to include a thread that will keep track of a timer(or a timer thread). My intention is to check the file size of /var/log/messages in every one minute & if the size is more than 128KB, do a echo " " > /var/log/messages, so that the file size will be set back to zero.
If somebody can help me with a sed command to check the size of messages & to do a echo "" > messages ,if the size is greater than 128KB, I'll really grateful.


Last edited by jockey007; 11-13-2007 at 03:47 PM.. Reason: typo
# 2  
Old 11-13-2007
You could actually use find!

find /var/log -name messages -type f -size +131072c

# 3  
Old 11-13-2007

Now I'm using a busybox find, which doesn't have support for "-size" argument
So i think a sed command that meets the requirement would be great.
Please provide a sed command to check the file & then flush that file.

# 4  
Old 11-13-2007
Then it would help to know how you intend to use sed.

What does the output from "ls -ld /var/log/messages" look like?
# 5  
Old 11-13-2007
Hi Porter,

The output of
root@WiMAX-BS:/var/log ls -ld /var/log/messages
-rw------- 1 root root 41994 Jan 23 03:16 /var/log/messages


Well.. I was thinking like
1) use the ls command grab the size value using the sed and
2) then if it is greater than 128KB, do an echo " " > /var/log/messages

Now I've crond support, so I can add a script with above logic to cron job.

# 6  
Old 11-13-2007


     echo $5

SIZE=`ls -ld $LOG`
SIZE=`fifth $SIZE`

if test "$SIZE" -gt 131072
      date >$LOG

# 7  
Old 11-13-2007

Oh!! That works!

Thanks a lot Porter...
Have a nice day.


Last edited by jockey007; 11-13-2007 at 09:10 PM..
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