Renaming all files in a directory while keeping the same initial part of the name

Question

I have a directory full of files. I want to rename all the files that match *.py to -backup.py. How do I do that.

I know I can use for i in *.py, but from there I'm not sure how to keep the initial name and just append backup to all of them.

score 1 · Answer 1 · edited Jul 02 '13 at 20:13

1

for i in *.py
do
    mv "$i" `echo "$i" | sed 's/\.py$/-backup.py/'`
done

edited Jul 02 '13 at 20:13

answered Jul 02 '13 at 20:03

unxnut

6,008

Thanks for the help. Not to impose, but could you also explain what's going on so I can implement similar solutions when this problem comes across? – dasElevator Jul 02 '13 at 20:06
Interesting...I might have used something with find so that on a HUGE directory I would hit the command line length limit. – mdpc Jul 02 '13 at 20:28
@dasElevator The for statement picks one file at a time that matches your criterion (.py extension) in the directory. The mv statement renames it. The last part of the mv uses sed to generate the name as per your specs. – unxnut Jul 02 '13 at 20:32

score 1 · Answer 2 · edited Dec 22 '20 at 18:46

1

The same as evilsoup with find:

find . -name '*.py' -exec bash -c 'mv "$1" "${1%.py}-backup.py"' _ {} \;

or if you don't like to launch an instance of bash for each file found:

find . -name '*.py' -exec bash -c 'for f; do mv "$f" "${f%.py}-backup.py"; done' _ {} +

The find solution might be better if you have a huge number of files, since bash globbing is slow. Feel free to add an -n option to mv (no clobber) or a -v option (verbose).

edited Dec 22 '20 at 18:46

αғsнιη

41,407

answered Jul 02 '13 at 21:52

gniourf_gniourf

1,519

More importantly than globbing being slow vs find (though ideally I'd like to see something backing that up), if you are working with a truly huge number of files, with globs you may run into the maximum number of arguments for bash. So if you're working with many hundreds of thousands of files, this is the way to go. (You can find out what the maximum number of arguments is on your system with echo "$(getconf ARG_MAX)/4-1" | bc). This is also POSIX (or it would be, if you replaced bash -c with sh -c), whereas globstar isn't. – evilsoup Jul 02 '13 at 22:05

evilsoup · Answer 3 · 2013-07-02T21:30:27.347

The essence of this is the same as unxnut's answer, but I think using sed for something as simple as stripping an extension is way overkill:

for f in ./*.py; do mv "$f" "${f%.py}-backup.py"; done

${f%.py} is the variable $f, with the .py stripped from the end. You can also remove things from the beginning with ${f#whatever}. For recursiveness (i.e. working in the current directory and all subdirectories), assuming you have bash 4+, you can use globstar:

shopt -s globstar
for f in ./**/*.py; do mv "$f" "${f%.py}-backup.py"; done

Alternatively, you can use rename -- there are actually two different programs that use this name, and which one you have will depend on your flavour of *nix. perl-rename (used by Debian and its derivatives, such as Ubuntu, and many others):

rename 's/\.py$/-rename.py/' ./*.py

The other rename would use this syntax:

rename .py -backup.py ./*.py

The for loop with mv is more portable, of course: the first, non-recursive one is POSIX, and so will work on every *nix anywhere, except maybe some museum pieces.

Renaming all files in a directory while keeping the same initial part of the name

3 Answers3