shell syntax

sh-rename.txt

Move all files with names ending in ".jpg" from the current folder to the Documents directory.

  $ mv *.jpg ~/Documents

____________________________
Move the "Documents" folder to "Documents backup". (quotes are needed because of the space in the folder name.)

  $ mv Documents "Documents backup".

____________________________
Rename .txt files to .html

  $ for f in *.txt; do mv ./"$f" "${f%txt}htm"; done