Cool Bash Commands

Remove the ABCD– prefix from a filename:
$ s='ABCD --11212239.pdf'
$ mv "$s" "${s#ABCD--}"

Remove the prefix from all files in current directory recursively:
while IFS= read -r -d '' filename; do
mv "$filename" "${filename#ABCD--}"
done < <(find . -type f -name 'ABCD--*' -print0)

Remove the .pdf suffix from a filename:
$ s='ABCD --11212239.pdf'
$ mv "$s" "${s%.pdf}"

Remove the suffix from all the files in the current directory recursively:
while IFS= read -r -d '' filename; do
mv "$filename" "${filename%.pdf}"
done < <(find . -type f -name '*.pdf' -print0)