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

jockey007 · #1 (**permalink**) 11-13-2007

Hi,

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.

Wishes
Jay

porter · #2 (**permalink**) 11-13-2007

You could actually use find!

Code:

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

jockey007 · #3 (**permalink**) 11-13-2007

Thanks....

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.

Wishes
Jay

porter · #4 (**permalink**) 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?

jockey007 · #5 (**permalink**) 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.

Thanks
Jay

porter · #6 (**permalink**) 11-13-2007

Code:

#!/bin/sh

LOG=/var/log/messages

fifth()
{
     echo $5
}

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

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

jockey007 · #7 (**permalink**) 11-13-2007

Oh!! That works!

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

Wishes
Jay

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Development Releases: Linux Mint 4.0 Beta "Fluxbox", 4.0 Alpha "Debian"	iBot	UNIX and Linux RSS News	0	01-04-2008 03:00 PM
Explain the line "mn_code=`env\|grep "..mn"\|awk -F"=" '{print $2}'`"	Lokesha	UNIX for Dummies Questions & Answers	4	12-20-2007 01:52 AM
check input = "empty" and "numeric"	geoffry	Shell Programming and Scripting	6	12-13-2007 05:12 AM
Command similar to "touch" for modify File size	sriharshareddyk	UNIX for Advanced & Expert Users	3	11-15-2007 01:43 AM
Maximum input file size in "Diff" Command	Neeraja	UNIX for Dummies Questions & Answers	1	01-17-2007 10:09 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread: