Get the newest file in a directory.

Shell Programming and Scripting
1

I am new to shell scripting so i need some help need how to go about with this problem.

I have a directory which contains files in the following format. The files are in a diretory called /incoming/external/data

    AA_20100806.dat
    AA_20100807.dat
    AA_20100808.dat
    AA_20100809.dat
    AA_20100810.dat
    AA_20100811.dat
    AA_20100812.dat

As you can see the filename of the file includes a timestamp. i.e. [RANGE]_[YYYYMMDD].dat

What i need to do is find out which of these files has the latest date using the timestamp that is part of the filename not the system timestamp and move it to another directory and move the rest to a different directory.

2

Assuming your RANGE is always AA

ls -1| tail -1 will give you the latest file.

3

Hi thanks for that. It seems to work but i cant work out how.
I looked at the manual for ls and it says that -1 "Prints one entry per line of output".

At what point does the sorting occur?

4

Hi.

The sort order of ls is alphabetical by default.

By using -1 it does print one entry per line, then tail -1 will take the last one (i.e. the newest by timestamp).

But you don't even need the -1:

$ touch AA_20100806.dat AA_20100807.dat AA_20100808.dat AA_20100809.dat AA_20100810.dat AA_20100811.dat AA_20100812.dat
$ ls
AA_20100806.dat	AA_20100807.dat	AA_20100808.dat	AA_20100809.dat	AA_20100810.dat	AA_20100811.dat	AA_20100812.dat
$ ls | tail -1
AA_20100812.dat
5

Oh ok i get it now. Thanks for you help.