Bulk renaming files using Mac's Bash. Prepending string to files of a given type.

Bash bulk rename

# You want to rename all files of a certain kind in a directory, 
# prepending an arbitrary string to file names.
# Put files in a folder and cd there in the terminal.

# This Example looks for any flash video files (.flv) 
# inside the current directory and prepends "movie_" to each file name.
# Here be magic:

  for f in *.flv; do mv "$f" "movie_$f"; done


# If file renaming produces error, check file permissions
  ls -lha
# if there are no 'w's under permissions: 
  chmod 755 *
# to make files writable.