Shell Programming and Scripting

hi,

i have some file in a directory say

Code:

p1.txt.201305051200.lst
p1.txt.201305051300.lst
p1.txt.201306051200.lst
p1.txt.201306051300.lst
p2.txt.201306051200.lst
p2.txt.201306051300.lst

i am using p* pattern to retrieve these file

Code:

ls -1 p*

the files in red color are the latest file of p1 and p2

i want to take the latest filenames of both p1 and p2 and write it to a file say filelist.txt.

can anyone give a code to retrieve the latest files of p1 and p2.

Latest by file arrived time? Or latest by ordering?
ls -1 wont list files as per file name sorting..

latest by arrived time.

---------- Post updated at 01:32 PM ---------- Previous update was at 01:30 PM ----------

but i want latest of both p1 and p2.

Try below..

Code:

 
ls -tr1 p*|awk -F"." '{A[$1]=$0}END{for(i in A){print A[i]}}'

ya it worked.
can you explain me the awk part of the command.

I am storing the file name as per p1,p2,p3 so on..

A[p1]=first file start with p1
if it finds second file with p1 it will overwrtie the content so u always left with latest filename as we are feeding ls -lt1 feed to awk. the same applies to A[p2], A[p3] etc...

will the above command work if i am using *.lst instead of p*

Code:

ls -tr1 *.lst|awk -F"." '{A[$1]=$0}END{for(i in A){print A[i]}}'

---------- Post updated at 01:54 PM ---------- Previous update was at 01:45 PM ----------

in the above code , you are dividing the file name in 4 fields

Code:

$1=p1
$2=txt
$3=201305051200
$4=lst

is it correct?

and then you are using

Code:

A[p1]=$0

, here $0 represents the full line if i am not wrong. i.e.

Code:

A[p1]=p1.txt.201305051200.lst

why in END used?

---------- Post updated at 02:14 PM ---------- Previous update was at 01:54 PM ----------

can you use full file name as index like p1.txt instead of just p1.
because if there are file like

Code:

p1.txt.201306051200.lst
p1.201306051200.lst

now there are two different files name one is p1.txt and the other is only p1.
so the above code just picks only one of the file.