can we do pattern macting based on a variable ??

u_Muhammad · 06-05-2010, 12:39 PM

i have the follwing code
touch umer.txt
fdisk -l | grep 'Disk /' umer.txt
read file
#now i want to check the 'file' string exits in the umer.txt or not
#i have
cat umer.txt | grep $file

but it is not workig...
how to do that ????

Robhogg · 06-05-2010, 01:09 PM

Simple answer, yes we can.

Have you checked that there's anything in the file umer.txt?

Quote:

fdisk -l | grep 'Disk /' umer.txt

This does nothing with the output of the fdisk command, and instad greps umer.txt for 'Disk /'. It should, I think, be:

Code:

fdisk -l | grep 'Disk /' > umer.txt # > is the redirect operator

Also, what pattern are you searching for (i.e. what are you entering at the "read" line)?

u_Muhammad · 06-05-2010, 01:23 PM

Yes sir, afer this cammad.
The file umer.txt contain
'Disk /dev/sda' and some other info.
now i want to check that if the user give input which is not in the umert.txt. then i will not work.
like if he enter abc then failed but if enters /dev/sda then continue.

Robhogg · 06-05-2010, 01:38 PM

So, are you wanting to do something like this?:

Code:

if ! cat umer.txt | grep $file; then 
      exit 1 # exit from script if no match
fi

It might help if you explain what it is that isn't working.

u_Muhammad · 06-05-2010, 01:59 PM

sir its not working....
it gives :
grep [option] pattern [File]

pixellany · 06-05-2010, 02:10 PM

Please post the actual commands you are using, and the resulting output (cut and paste from the terminal). Also, put the code into [code] tags. (Advanced mode--select the text, and click on #)

Robhogg · 06-05-2010, 02:11 PM

Quote:

Originally Posted by u_Muhammad

grep [option] pattern [File]

Which means, I believe, that what you are entering is not a valid pattern for grep.

Could you give an example of what you are entering, please, and the full output.

u_Muhammad · 06-05-2010, 02:47 PM

Sir, i have done it. Actually i was putting it in double quotes i think thats why it is giving error.
Thank you for your kind attention.