This gist is a collection of random things i've needed to do on the command line. Usually it is moving files around or scripting commands to run over a set of files.

rename-files.sh

#
# Source, a directory full of files like: t01-open.png, t02-open.png, etc. 
# Output, rename the files so t01-open.png turns into t00-open.png (start at zero instead of 1)

# loop through all the numbers ...
for i in {1..20} 
do 
    # turn 1, 2, 3, 4... into 01, 02, 03, 04
    f=$(echo $i | awk '{printf "%02s", $1}')

    # turn 1, 2, 3, 4... into 00, 01, 02, 00
    # math is done w/ the expr command
    v=$(expr $i - 1 | awk '{printf "%02s", $1}')

    # move the old file name to the new file name...
    mv t$f-close.png  t$v-close.png 
done