Rename and convert dates in filename without file extension

Question

My set of files are named according to GMT time zone. I successfully renamed and converted all files into the required time zone using the following steps.

1. This code removes all file extensions that are .gif rename "s/.gif//g" *

2. This code converts and renames all files for f in *; do mv -v -- "$f" "$(date -d "$f" '+%Y%m%d%H%M')"; done

• Example conversion: ‘15Z29Aug2017’ -> ‘201708292030’

Unfortunately I have to set the extension .gif once again to all files using for f in *; do mv "$f" "$f.gif"; done

How exactly can I skip the file extension removal by editing my code in step 2 ?

Step 2 taken from: How can I batch convert folder names from one date format to another

Answer 1

All you need is to strip .gif from $f and put it back on:

for f in *; do mv -v -- "$f" "$(date -d "${f%%.gif}" '+%Y%m%d%H%M')".gif; done

${f%%.gif} takes variable f and removes the last (hence # two times) occurence of .gif in it, so even a strange filename like 1.gif2.gif would only get his last .gif removed. This amazing feature is called Bash Parameter Expansion and when you search it by this name you can read all about its dazzling power, e. g. on this Bash FAQ – it's capable of so much more!