Shell Programming and Scripting

Hi all,

I need help in getting a particular string from the file name.let me describe my need, i have a directory that has different kind of files

for Eg:

fileone_rat_21012009.txt
filetwo_new_file_21012009.txt
file_old_ntn4_21012009.txt

i have different file formats but all the files end with "_21012009.txt" , here i need to get only the date ie " "21012009" from any one of the file present at the moment in the diretory.

please help me. Thanks in advance.

Code:

ls | egrep -o "21012009"

That would get only the date.

However, if you are wanting to get the date portion from the file name, for any possible date, then you could do..

Code:

ls | egrep -o "[0-3]?[0-9][01]?[0-9]2[0-9]{3}"

Or an easier way without regex.

Code:

ls | awk -F_ '{print $(NF) | "cut -d. -f1"}'

Of course you will need to weed out any other files that may be in there..

There's no need for an external command:

Code:

set -- *
temp=${1##*_}
date=${temp%.txt}

printf "%s\n" "$date"

Wow, I am um lost now..

Could you please explain the variable assignment? (and the set -- * ). Thanks!

Thanks you both !!!!, it worked .