Shell Programming and Scripting

I have task in which I need to pickup a set of files from a directory
depending on the following criteria:
Every month 6 files are expected to arrive at /test.
The files come with date timestamp and the latest file set for the month needs to be used
Suppose this is the set of files that present in the test directory
1. a_20080905_214058_200808.txt
2. b_20080905_214058_200808.txt
3. c_20080905_214058_200808.txt
4. d_20080905_214058_200808.txt
5. e_20080905_214058_200808.txt
6. f_20080905_214058_200808.txt
7. a_20080906_214058_200809.txt
8. b_20080906_214058_200809.txt
9. c_20080906_214058_200809.txt
10. d_20080906_214058_200809.txt
11. e_20080906_214058_200809.txt
12. f_20080906_214058_200809.txt
13. d_20080906_114058_200809.txt
14. e_20080906_114058_200809.txt
15. f_20080906_114058_200809.txt
Then
7. a_20080906_214058_200809.txt
8. b_20080906_214058_200809.txt
9. c_20080906_214058_200809.txt
10. d_20080906_214058_200809.txt
11. e_20080906_214058_200809.txt
12. f_20080906_214058_200809.txt files should be picked up.
Criteria 200809 is the latest month 20080906 is the latest date and 214058 is the latest date.
Thanks in Advance

Code:

/bin/ls -1 *_* |
  cut -d_ -f4 |
  sort -rnu |
  head -1 |
  read latest
 
/bin/ls -l *${latest}*

What's wrong with just doing this?

ls -r1 ?_*.txt | head -6

You can then just add some while logic around that.

assume you have a file with the filenames - call it inputfile - this is a longer example - plus -rnu will not work across _ characters.

Code:

tr -s '_' ' ' <  inputfile | \
  sort -n -k 1.1,1.1 -k 2.1,2.8 -k 3.1,3.6 | \
  awk '{ arr[$1]=$0 } END {for (i in arr) { print arr[i] } }' | \
  tr '_' ' ' | sort > resultsfile

i'm only pulling out the 4th field and piping to sort -rn.
( I tested it first; it works. )

My assumption was that the files were ~named~ with the
correct time-stamps, but the modification times on the files
themselves weren't necessarily correct....

If the file-modification-times are correct,
giannicello's solution works fine.

Thanks All,

Jim, The results file had file names with '_' replaced by spaces.How can that be corrected?
The filemodification time is not consistent and hence would not solve the purpose.
Thanks