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How to determine the name of the current working file in a regex operation?

rated 0 times [ 5] [ 0] / answers: 1 / hits: 486 / 2 Years ago, mon, february 28, 2022, 10:38:27

If I try to run a regex operation on files like so (example):

$ mv *.ext *.new.ext

That does not work.

How do I ensure that when I batch rename or perform an operation on multiple files that they keep their current name (not the extension, just the name)?

Note: I am not looking for something like the rename command because this has to work for everything, not just renaming files.

Note 2: Okay, these answers are good and explains things to me that I didn't properly understand before. Thanks!

The command in question I am trying to use is called firmtool, and is used in the 3DS homebrew scene.

It packs .bin files into .firm files and I would like it to run on all .bin files in a directory, packing them while preserving the original name.

Here is the syntax I need for the firmtool command:

firmtool build test.firm -n 0x23F00000 -e 0 -D arm9loaderhax.bin -A 0x23F00000 -C NDMA

where test.firm is the output and arm9loaderhax.bin is the input.

I want to run this command that if I have a directory with test1.bin and test2.bin that it produces test1.firm and test2.firm. Please let me know if I can use regular expression or a loop to complete this command. Thank you for any help!

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2 Years ago

answered 2 Years ago ickump · Accepted Answer

Hmm. You can't¹, not universally.

* is a wildcard. The shell expands it. When you type

*.ext

The shell expands it to a list of all the matching files, like:

1.ext 2.ext whatever.ext

That is what is passed to the command, in your case mv. If mv receives more than two arguments, the last must be a directory, so

mv *.ext *.new

fails with *.new is not a directory, because mv is receiving a long list of arguments.

The shell itself does not support regex, but Linux has many utilities that do, like perl rename...

rename -n 's/(.*).ext/$1.new/' *

And remove -n after testing to really rename...

But you can capture the varying names in a variable and use it to loop over the files...

for f in *.ext; do echo mv -v -- "$f" "${f/.ext/.new}"; done

and remove echo after testing to complete the renaming... You can use almost any command with for, not only mv. Here's a slightly different example based on your question:

for f in *.bin; do

  firmtool build "${f%.bin}.firm" -n 0x23F00000 -e 0 -D "$f" -A 0x23F00000 -C NDMA

done

In this case ${f%.bin} will expand to the value of the variable f with the suffix .bin stripped off (if it has such a suffix; otherwise it expands to the value of f).

See the manual on Shell Parameter Expansion for other expansion types.

¹_{waits to be proved wrong}