Problem

You want to replace the spaces in filenames (ie in Brennan’s B2 system), that uses busybox and you do not have all the linux commands available.

Solution

Use the following in the directory with the files (ie flac files). At the moment this command only works in the directory that is being run.

# find . -type f -name "*.flac" -exec ash -c 'mv "$0" "${0// /_}"' '{}' ';'