Shell Programming and Scripting

First, you can't have two files in a directory with the same name. Do some of your filenames contain backspace characters that disappeared when you copied your filenames into the lists above?

You can make up expressions that might work for any particular list you have to work with, but we're just wasting our time doing so. You need to clearly define the format of names you want to keep and the format of names of files you want to "filter out". Then you can look for an expression (or set of expressions) that can reliably determine which files to keep and which files to "filter out".

And what does "filter out" mean? Before, you said you wanted to truncate the contents of files. Now, you're talking about retaining some files and other files get filtered out???

Code:

#!/bin/ksh
for fn in sample*
do	[ "$fn" != "${fn%*[0-9][0-9]*}" ] && printf 'filter out %s\n' "$fn" || printf 'retain %s\n' "$fn"
done