rename series of files which differ in extension within the same directory using terminal

Question

I have a series of files which differ in extension (for example, a.txt, a.ps, a.pdf, etc.) and would like to copy them to a series of new files with a different name (b.txt, b.ps, b.pdf, etc.), preferably using terminal as I am running all other necessary operations from there. Years ago, I used to be able to do this on a PC from command prompt quite simply with:

copy d.* a.*

while in the working directory.

I'm having trouble figuring out/finding the corresponding OSX command. Feel like I am missing something obvious here, but just cannot sort it out.

Help much appreciated. Thanks for your time.

Answer 1

This command would seem to do what you wish

for file in *.* ; do cp $file ${file//a\./b\.} ; done

Adapted from this answer to Renaming part of a filename

Actually, you could just do:

for file in * ; do cp $file ${file//a\./b\.} ; done

Note that the . has to be escaped using \.. This is primarily because your example is a filename of a single letter, which could potentially conflict with a letter in the extension.

If your filenames are a bit more explicit, such as doggy.txt, doggy.pdf, doggy.xls, etc., and you want to change them to feline.txt, feline.pdf, ..., etc., then you could do away with escaping the . (and the . all together), like so:

for file in * ; do cp $file ${file//doggy/feline} ; done

---

Note that the commands above will create a copy of the files, i.e.:

% ls
a.pdf   a.txt   a.xls   b.pdf   b.txt   b.xls

If you wish to just rename them, then use mv instead:

for file in * ; do mv $file ${file//a\./b\.} ; done

or

for file in * ; do mv $file ${file//doggy/feline} ; done