Infrastructure Software

Hello friends,

How to gunzip recent 4 files only
when i do the following
[little@linux test]$ ls -ltr|tail
-rw-r--r-- 1 little devlp 130 Mar 21 09:00 commwho080321090000.gz
-rw-r--r-- 1 little devlp 130 Mar 21 09:30 commwho080321093000.gz
-rw-r--r-- 1 little devlp 130 Mar 21 10:00 commwho080321100000.gz
-rw-r--r-- 1 little devlp 130 Mar 21 10:30 commwho080321103000.gz
-rw-r--r-- 1 little devlp 152 Mar 21 11:00 commwho080321110000.gz
-rw-r--r-- 1 little devlp 152 Mar 21 11:30 commwho080321113000.gz
-rw-r--r-- 1 little devlp 152 Mar 21 12:00 commwho080321120000.gz
-rw-r--r-- 1 little devlp 152 Mar 21 12:30 commwho080321123000.gz
-rw-r--r-- 1 little devlp 180 Mar 21 13:00 commwho080321010000.gz
drwxr-xr-x 2 little devlp 4096 Mar 21 13:16 backup
[little@linux test]$ ls -ltr|tail -4 | gunzip *
gunzip: backup is a directory -- ignored
ls: commwho080321083000.gz: No such file or directory
[little@linux test]$ l
-rw-r--r-- 1 little devlp 142 Mar 21 09:00 commwho080321090000
-rw-r--r-- 1 little devlp 142 Mar 21 09:30 commwho080321093000
-rw-r--r-- 1 little devlp 142 Mar 21 10:00 commwho080321100000
-rw-r--r-- 1 little devlp 142 Mar 21 10:30 commwho080321103000
-rw-r--r-- 1 little devlp 191 Mar 21 11:00 commwho080321110000
-rw-r--r-- 1 little devlp 191 Mar 21 11:30 commwho080321113000
-rw-r--r-- 1 little devlp 191 Mar 21 12:00 commwho080321120000
-rw-r--r-- 1 little devlp 191 Mar 21 12:30 commwho080321123000
-rw-r--r-- 1 little devlp 249 Mar 21 13:00 commwho080321010000
drwxr-xr-x 2 little devlp 4096 Mar 21 13:16 backup

All files are gunziped

please tell me how to do so