linux - changing order of files

I have a series of files named in alphabetical order (xaa.tif to xdg.tif). I need to reverse the order of the filenames so that the last file is processed first in a script. I would like to rename them by adding a number at the beginning of the filename (01xdg.tif to 60xaa.tif).

How can I do that with a bash script on Linux?

Because the file names contain no special characters, including spaces, this can be pretty easily accomplished using ls -r (that's -r for --reverse, not -R for --recursive).

/tmp/todo$ ls
/tmp/todo$ touch ab bc bd ef
/tmp/todo$ ls
ab  bc  bd  ef
/tmp/todo$ ls -r
ef  bd  bc  ab
/tmp/todo$

Then you can rename the files using something like:

num=1
for file in $(ls -r)
do
    mv $file "$(seq --format='%02g' $num $num)${file}"
    num=$(( $num + 1 ))
done

This uses seq to format the number to use two digits (2) zero-padded from the left (%0) with no decimal places (g) for a total format string of %02g. There's probably a more efficient way to do it, but with so few files, I wouldn't bother micro-optimizing.

This simply iterates over the list of files (in reverse order), renames each one in turn and increments a counter for each rename.

The final result is:

/tmp/todo$ ls
01ef  02bd  03bc  04ab
/tmp/todo$

Note that the above may very well fall apart if the file names have anything more unusual in them than simple a-z, periods and digits to begin with. Particularly, I'm not sure how well it'll handle spaces.

You can user sort command in Linux

lets say the directory contains following files

# ll /tmp/sort_folder
total 0
-rw-r--r-- 1 root root 0 Dec 18 19:51 a
-rw-r--r-- 1 root root 0 Dec 18 19:51 b
-rw-r--r-- 1 root root 0 Dec 18 19:51 v

The sort command will give you output as below(by default ascending)

# ll /tmp/sort_folder | sort
-rw-r--r-- 1 root root 0 Dec 18 19:51 a
-rw-r--r-- 1 root root 0 Dec 18 19:51 b
-rw-r--r-- 1 root root 0 Dec 18 19:51 v

To reverse sort(descending) you can we -r(reverse) option for sort command

# ll /tmp/sort_folder | sort -r
total 0
-rw-r--r-- 1 root root 0 Dec 18 19:51 v
-rw-r--r-- 1 root root 0 Dec 18 19:51 b
-rw-r--r-- 1 root root 0 Dec 18 19:51 a

This should work:

#!/bin/bash
#
Count=0
ls -r | while read FileName
do
    FmtCount=`printf %02d $Count`
    mv -i $FileName $FmtCount$FileName
    Count=$((Count+1))
done

Here's the explanation:

• ls -r lists the files in reverse order
• printf formats the count into two zero-padded digits
• The backquotes turn the output into a string

I think the rest is self-explanatory, but if not please ask