关于unix重命名

# change file name
mv -f old_file new_file

# rename all files'extension to 'bak' in the directory.
for i in $(ls *.*); do   mv -f $i ${i%.*}.bak; done

# rename all files with special pattern to 'bak' in the directory.
for i in $(ls *.doc); do   mv -f $i ${i%.doc}.bak; done