Reverse filename

[matrooswolf]

Hi,
Is there an easy way to reverse filenames? Example: abcdef.jpg becomes fedcba.jpg.

[steeldriver]

You can use the rev command

DESCRIPTION
     The rev utility copies the specified files to standard output, reversing
     the order of characters in every line.  If no files are specified, stan‐
     dard input is read.

If you don't want to reverse the suffix as well, you will need to remove and replace it e.g.

$ f="abcdef.jpg"
$ 
$ r="$(rev <<< "${f%.*}").${f##*.}"
$ 
$ echo "$r"
fedcba.jpg

[matrooswolf]

Thanks for mentioning the rev command. Does it actually reverse the filename on disk (this it what I want), or does it simply make a string of the reverse characters?

[Vaphell]

it's a string that can be plugged into mv command, thus solving your problem

in steeldriver's example it would be

mv "$f" "$r"

[matrooswolf]

Thanks for explaining, vaphell.
Is there a way to combine the rev and mv command in one command that I could reuse, while simply replacing the filename?

[steeldriver]

Well you could just do a "one-liner" to loop over the list of files, like

for f in *.jpg; do echo mv "$f" "$(rev <<< "${f%.*}").${f##*.}"; done

However I thought about this some more in the meantime - since Ubuntu provides the perl-based rename command, and perl has its own string reverse function, you should be able to do something like

rename -vn -- 's/(.*)[.]([^.]*)$/join(".",my $rev=reverse($1),$2)/e' *.jpg
abcdef.jpg renamed as fedcba.jpg
pqrstu.jpg renamed as utsrqp.jpg

The -n option is only for testing purposes.