File being used/written

#1 (**permalink**) 10-12-2001

Hello,
Which command in unix can tell whether a file is being used/written by another process.

e.g. If one process is copying a very big file in some directory and there is another cronjob process which checks for a new file and in this directory and process the file. I want to check, if the file is still being written by the last process.

Sanjay

#2 (**permalink**) 10-12-2001

Code:

#!/bin/ksh

x=`cksum File_Name.exp | awk '{print $1}'`
#sleep 1
y=`cksum File_Name | awk '{print $1}'`
if [  $x = $y ] ; then
  echo "Both are same" $x $y
else
  echo "Both are different" $x $y
fi

This method will work to find out, if the file is still being written by comparing the two snapshots of checksum of file.

Is there any other good method ?

Thanks for taking your time.

Sanjay

added code tags for readability --oombera

rwb1959 · #3 (**permalink**) 10-12-2001

If you have lsof you can use that to see
what files are open. You can use...
lsof -F File_Name.exp
...and use that output. I would suggest reading
the man page carefully though. There are alot
of "note" and options.

All said and done though your solution appears
to be simple and if it works...I say stick
with it.

#4 (**permalink**) 10-13-2001

Thanks for reply.
Unfortunately, I did not find isof utility/command in my unix system. I have SunOS 5.6 Generic_105181-23 sun4u sparc SUNW,Ultra-Enterprise.
Is this utility has to be installed seprately or may be not in my path listing and also I did not find man isof as well.

Sanjay

rwb1959 · #5 (**permalink**) 10-13-2001

Yes. It normally isn't installed (until revently).
You'll have to go get it, build it and install
it.

Go to this link...
http://www.cert.org/security-improve...s/i042.05.html

...it's the best reference for me...

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