topic Re: Script Help in Operating System - Linux

Script Help

Thad Jones — Sun, 08 Apr 2007 10:14:20 GMT

Hello All

I am trying to write a script that would be used to populate a file of the same size (approx 300K) onto a 1TB filesystem and then repeat the process until the filesystem is 100% filled.

I am not sure how to write the code for this at all.

Being that I am a newbie to this forum and linux in general as much help as you can provide here would be very much appreciated.

Thank you all and Happy Easter.

Re: Script Help

Ivan Ferreira — Sun, 08 Apr 2007 12:14:39 GMT

First, consider the number of inodes. if you run out of inodes you cannot write more files. You specify the number of inodes for a file system in the mkfs command.

Re: Script Help

Ivan Ferreira — Sun, 08 Apr 2007 12:53:42 GMT

You can use a script like this:

COUNT=0
while true
do
dd if=/dev/zero of=file$COUNT bs=300k
COUNT=`expr $COUNT + 1`
done

Re: Script Help

Thad Jones — Sun, 08 Apr 2007 18:57:50 GMT

Thank you for the reply.

I tried this script on my system and it builds one large file which is ok but what i am trying to do is build the same file size (300k or another size) and multiply it across the entire filesystem making millions of little files on a 1TB filesystem.

What should i do to the script you supplied in order to tweak it to the correct output i desire.

Thanks again.

Re: Script Help

Stuart Browne — Sun, 08 Apr 2007 23:39:43 GMT

Umm, nothing. That script will work as it is.

But the issue does reside in the fact that you'll probably run out of inodes before you run out of space using 300k files. If so, use larger files.

Re: Script Help

Rasheed Tamton — Mon, 09 Apr 2007 00:55:25 GMT

Hello

What is the real objective here. Are you looking to wipe out the disk.

Regards.

Re: Script Help

Ivan Ferreira — Mon, 09 Apr 2007 08:26:34 GMT

You are right, one thing is missing in the script, try this:

COUNT=0
while true
do
dd if=/dev/zero of=file$COUNT bs=300k count=1
COUNT=`expr $COUNT + 1`
done

Re: Script Help

Thad Jones — Mon, 09 Apr 2007 15:39:46 GMT

Thanks again for the post Ivan. That worked fine.

Now just to add more to my confusion, i was told that they wanted to change this up a little bit so here goes what i need to do:

1) The application's output directory structure creates 100 directories called 00 thru 99.

2) since the filesystem size is 1TB and were using an output file size of 300K, if my math is correct that would equate out to about 3 million files for the whole filesystem.

3) based on #1 & #2, what i have to do now is take the script you provided me and let it write 30,000 files per directory while walking each directory and doing the same thing until it reaches the 99 directory.

Hope this is a simple thing for you cause it sure has me confused.

Thanks again

Re: Script Help

Sreedharamurthy K — Mon, 09 Apr 2007 19:25:54 GMT

IT is simple. Put the while script above in a for loop which creates 100 directories. Run that script at the top directory.

Something like this...

LIMIT=100

for ((a=1; a <= LIMIT ; a++))
do
mkdir dir$a
cd "dir$a"

cd ..
done

Re: Script Help

Thad Jones — Mon, 09 Apr 2007 19:47:59 GMT

I will try that but one question here.

What can i do to limit the number of files created to 30,000 total per directory thus giving me 3 million files total?

Thanks for the help, it is much appreciated.

Re: Script Help

Sreedharamurthy K — Mon, 09 Apr 2007 23:40:39 GMT

to limit, change the condition in while loop:

instead of while true change it to

while [ $COUNT â le 30000 ]

Re: Script Help

Sreedharamurthy K — Mon, 09 Apr 2007 23:43:00 GMT

You can refer to this guide. Has good examples and scripting info:

http://www.tldp.org/LDP/abs/abs-guide.pdf

Re: Script Help

Thad Jones — Tue, 10 Apr 2007 07:42:07 GMT

The last line you wrote there came across with a bunch of special characters.

How would the while statement be coded as?

Thanks.

Re: Script Help

Court Campbell — Tue, 10 Apr 2007 12:07:33 GMT

the Ã¢ should be a dash.

Re: Script Help

Court Campbell — Tue, 10 Apr 2007 12:10:37 GMT

wow, copying and pasting the crazy 'a' changed it to another character.

Re: Script Help

Sreedharamurthy K — Tue, 10 Apr 2007 12:35:21 GMT

Oh!! I didn't realize that copy paste would have changed it..

Thanks.. :)

Yes, it is -le

Re: Script Help

Court Campbell — Tue, 10 Apr 2007 13:04:12 GMT

Thad,

I think you should assign some points to Sreedharamurthy K. He has only done your work for you.

Re: Script Help

Court Campbell — Tue, 10 Apr 2007 13:05:10 GMT

Oh,

And Ivan as well.

Re: Script Help

Thad Jones — Tue, 10 Apr 2007 13:33:57 GMT

Thank you all, this worked to perfection.

Kudos to all of you and yes points are forthcoming as well

BZ to all.

This forum rocks.