===== Bash =====

==== rename a_file to lower case ====
For each file a_file in current directory rename a_file to lower case.
<code bash>for a_file in *;do mv -v "$a_file" `echo "$a_file" | tr [:upper:] [:lower:]` ;done; </code>
((https://askubuntu.com/questions/282794/batch-rename-files-to-lowercase))
For upper case reverse the arguments to [:lower:] [:upper:]
<code bash>for a_file in *;do mv -v "$a_file" `echo "$a_file" | tr [:lower:] [:upper:]` ;done; </code>