Some reasons you might want to lowercase your filenames include:
1. Most webservers are case-sensitive. Because of this, most websites stick to the rule of having all files in a single case, namely lower.
2. If you’re using the command line to manipulate files, it’s easier when all the files are lower case. It’s a lot faster to type in all one case.
But it’s too time consuming to rename each file individually, so here are a few ways to rename. These are adapted from the commandlinefu website. (But the commands there have some bugs, so keep reading here.)
Renaming all the files in the current directory from uppercase to lowercase
rename 'y/A-Z/a-z/' *
This uses the rename script which is included with Perl, which in turn uses Perl’s rename function.
Most Linuxes and Unixes include Perl these days, including most web hosts. It’s easier and more succint than the alternatives.
Renaming all files from uppercase to lowercase in the current and subdirectories recursively
The way to do this is to feed rename a list of all files in the current directory and its subdirectories:
find . -type f -print0 | xargs -0 rename 'y/A-Z/a-z/'
Here’s what it means:
find prints a list of all files in the current and all subdirectories, recursively. -type f means only print the names of files, and not directories.
The | takes the output of the first command and sends it as input to the second command.
xargs takes the input (which is a list of files) and executes rename once for every filename, while appending the filename to the end of the rename command.
Normally, find puts a newline between each filename. But since a file’s name can also contain newlines, you make find delimit the filenames with a null character (ASCII 0). You do this by specifying the -print0 option. But you also have to tell xargs not to view newlines or spaces as filename delimiters, but rather only the null character. You do that with the -0 option.
Renaming files to lowercase without using Perl
Occasionally, you might not have access to Perl.
In such cases, you can use straight POSIX shell commands:
find . -type f|while read f; do mv "$f" "$(echo $f|tr '[:upper:]' '[:lower:]')"; done
This is an alernative that’s faster:
find . -type f -execdir sh -c 'mv "'{}'" "$(echo '{}'|tr '[:upper:]' '[:lower:]')"' \;
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