Question

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Renaming lots of files in Linux according to a pattern

I have multiple files in this format:

file_1.pdf
file_2.pdf
...
file_100.pdf

My question is how can I rename all files, that look like this:

file_001.pdf
file_002.pdf
...
file_100.pdf

I know you can rename multiple files with ‘rename’, but I don’t know how to do this in this case.

Answer 1

You can do this using the Perl tool rename from the shell prompt. (There are other tools with the same name which may or may not be able to do this, so be careful.)

rename 's/(\d+)/sprintf("%03d", $1)/e' *.pdf

If you want to do a dry run to make sure you don’t clobber any files, add the -n switch to the command.

note

If you run the following command (linux)

$ file $(readlink -f $(type -p rename))

and you have a result like

.../rename: Perl script, ASCII text executable

then this seems to be the right tool =)

This seems to be the default rename command on Ubuntu.

To make it the default on Debian and derivative like Ubuntu :

sudo update-alternatives --set rename /path/to/rename

Explanations

• s/// is the base substitution expression : s/to_replace/replaced/, check perldoc perlre
• (\d+) capture with () at least one integer : \d or more : + in $1
• sprintf("%03d", $1) sprintf is like printf, but not used to print but to format a string with the same syntax. %03d is for zero padding, and $1 is the captured string. Check perldoc -f sprintf
• the later perl’s function is permited because of the e modifier at the end of the expression