split string

how to split string in a directory.

ex: file name is atk_wip_2004102345line.logs.
how i'm gonna split to just have the date?
=20041023 only?

in your example
echo atk_wip_2004102345line.logs ¦ sed 's/\(.*\)\([0-9]*[0-9]\)\(.*\)/\2/'

it can't work..can i used echo atk_wip_2004102345line.logs | sed 's/\_/ /g' ? but it looks like removind the '_'.how can i display '2004102345'?

sed 's/\(.*_\)\([0-9]*[0-9]\)\(.*\)/\2/'

its work..
but i can't passed that value to variable.
ok let say the file name is 7B1_WIP_20041120010436.11497972948866630.xml.dat

surely i can used sed u say just now. there will return
20041120010436 only.

what can do to just have the date?=20041120

do we need to use sed 2 times?
help!!

sed 's/\(.*_\)\([0-9]\{8\}\)\(.*\)/\2/'

??? but i can't passed that value to variable.
VAR=`sed '....'`
echo $VAR

..thanks...done

thanks..
but may be u think i'm gonna pass the input variable

actually, i's going to use back the value to compate with currebt date.
let say:
for file in ls ATK*
do
file2=$file | sed 's/\(.*_\)\([0-9]\{8\}\)\(.*\)/\2/'
if $file2 = date +%Y%m%d
then
echo "file updated"
fi
done

-->$file2 means variable passed after sed function perform.

or simple words is..how we use the output of sed function as another input?
sorry..i'm quite dump in this programming language

hi izza
may i kindly invite you to read a (shell) book ?
before writing scripts, think about what you try to do and
the simpliest way to do it.

TODAY=`date +%Y%m%d`
for file in `ls ATK*`
do case $file in *$TODAY*) XX= ;; *) XX=not ;; esac
echo $file $XX updated
done
------------------ an other way
ls ATK*$TODAY* 2>/dev/null && echo UPDATED
-------------------
i let you correct your script, all programming languages are
not trivial, but (bourne)shell is pretty easy, the rest is logic.
in your exp. on every matching filenames
- you start a sed to cut the filename (do it once)
- corollary, the fname could be duplicated !!!
- compute the date (a constant, do it once)
- all this work for what ? on a big directory it could be
a performance issue.

- finally, dont trust the date in the filename, use 'stat()'
in perl, but this is an other && distant chapter.