Ubuntu – Batch rename directories

For each file a_file in current directory rename a_file to lower case.

for a_file in *;do mv -v "$a_file" `echo "$a_file" | tr [:upper:] [:lower:]` ;done;

For upper case reverse the arguments to [:lower:] [:upper:]

tr command reference link

Update

For even more control * can be replaced with ls.

For example in a directory containing 1.txt, 2.txt, 3.txt, 1.jpg, 2.jpg and 3.jpg in order to filter only *.jpg files, ls can be used:

for a_file in $(ls *.jpg);do mv -v $a_file `echo $a_file | tr [:upper:] [:lower:]` ;done;

The above code will assign to a_file variable all files with .jpg extension.

Update added -v option to mv command as per sds suggested.

Try the following:

find /path/to/parrent-dir -type f -exec rename -n 's:[^/]*(.*) .*$:$1:' {} +

./o7th.ico (NEWER_1417529135.81)                                 renamed as /o7th.ico
./sub-dir (NEWER_1417529135.81)/getyou.ico (NEWER_1417529079.87) renamed as /sub-dir (NEWER_1417529135.81)/getyou.ico
./sub-dir (NEWER_1417529135.81)/o7pm.ico (NEWER_1417529184.89)   renamed as /sub-dir (NEWER_1417529135.81)/o7pm.ico
./getyou.ico (NEWER_1417529079.87)                               renamed as /getyou.ico
./o7pm.ico (NEWER_1417529184.89)                                 renamed as /o7pm.ico

• All [^/]*(.*) .*$ matches only the last part of the path that doesn't contain a /. And
• In above regex, (.*) is a group of matching everything after last / and before a space. Its back-reference will be $1.
• .*$ matches everything to end$ of files name after space.
• Finally in replacement part of rename s/.../REPLACEMENT/, we just kept the matched group that is between last \ and a space(.*) which is known as group of matches.