Both these commands work on most Linux and OSX/Mac machines.
Replace spaces with dashes in files in a directory
find . -depth -name "* *" -execdir rename 's/ /-/g' "{}" \;
Replace a range of characers using a regular expression.
This this will remove any characters not matching a-z (lower and upper case), numbers, and dashes and replace them with a dash. You can change the dash with any character you want by replacing the dash in the shell line below right before the ending g /-/g. It only does the replacements in the current directory. You can limit the files with the * file mask change. Like change to *.txt to only to .txt files.
rename 's/[^a-zA-Z0-9]-/-/g' *
