I have a bash script which I'm trying to get to replace dots in filenames and replace them with underscores, leaving the extension intact (I'm on Centos 6 btw). As you can see from the output below, the script works when there is a dot to replace, but in cases where the only dot is the extension, the script still tries to rename the file, instead of ignoring it. Can anyone point out how I should handle this better? Thanks for any help.
My (faulty) script:
#!/bin/bash
for THISFILE in *
do
filename=${THISFILE%\.*}
extension=${THISFILE##*\.}
newname=${filename//./_}
echo "mv $THISFILE ${newname}.${extension}"
#mv $THISFILE ${newname}.${extension}
done
Sample input:
1.3MN-Pin-Eurotunnel-Stw505.51.024-EGS-130x130.jpg
Wear-Plates.jpg
Output:
mv 1_3MN-Pin-Eurotunnel-Stw505_51_024-EGS1-130x130.jpg 1_3MN-Pin-Eurotunnel-Stw505_51_024-EGS1-130x130.jpg
mv Wear-Plates_jpg.Wear-Plates_jpg Wear-Plates_jpg.Wear-Plates_jpg
Best Answer
I believe that this program will do what you want. I have tested it and it works on several interesting cases (such as no extension at all):
The main issue you had was that the
##
expansion wasn't doing what you wanted. I've always considered shell parameter expansion in bash to be something of a black art. The explanations in the manual are not completely clear, and they lack any supporting examples of how the expansion is supposed to work. They're also rather cryptic.Personally, I would've written a small script in
sed
that fiddled the name the way I wanted, or written a small script inperl
that just did the whole thing. One of the other people who answered took that approach.One other thing I would like to point out is my use of quoting. Every time I do anything with shell scripts I remind people to be very careful with their quoting. A huge source of problems in shell scripts is the shell interpreting things it's not supposed to. And the quoting rules are far from obvious. I believe this shell script is free of quoting issues.