Shell Programming and Scripting

1) This is this "grep -l" part which cost the most that why the second command (which didn't run this part) was quicker.
Also if you run that second command after the first one, maybe the filnames were already in the cache because of the previous 45min command which may have done the heaviest part of the job

2) By default ls does a sorting by name which may be very consumming as well as painfull from performance point of view if you have a bunch of files (in your example : around 30000 xml files in a directory).

In such case you can use the -f option of the ls command (or -U or any equivalent option depending on your OS) so ls won't sort, and will take the file directly one after the other as they appear in the node structure which may be a lot faster than sorting them, especially when they are numerous.

Code:

ls -f | grep xml$ | xargs -n5 grep -l "Status"

or

Code:

ls -U | grep xml$ | xargs -n5 grep -l "Status"

or check your

Code:

man ls