Rsync compare directories

To see a listing, here are two variants, one that recurses into subdirectories and one that doesn't. All use syntax specific to bash, ksh and zsh.

comm -3 <(cd source && find -type f | sed 's/\.[^.]*$//' | sort) \
        <(cd dest && find -type f | sed 's/\.[^.]*$//' | sort)
comm -3 <(cd source && for x in *; do printf '%s\n' "${x%.*}"; done | sort) \
        <(cd dest && for x in *; do printf '%s\n' "${x%.*}"; done | sort)

Shorter, in zsh:

comm -3 <(cd source && print -lr **/*(:r)) <(cd dest && print -lr **/*(:r))
comm -3 <(print -lr source/*(:t:r)) <(print -lr dest/*(:t:r))

The comm command lists the lines that are common to two files (comm -12), that are only in the first file (comm -23) or that are only in the second file (comm -13). The numbers indicate what is subtracted from the output¹. The two input files must be sorted.

Here, the files are in fact the output of a command. The shell evaluates the <(…) construct by providing a “fake” file (a FIFO or a /dev/fd/ named file descriptor) as the argument to the command.

¹ _{So here the minus sayers are fully justified.}

If you want to perform actions on the files, you'll probably want to iterate over the source files.

cd source
for x in *; do
  set -- "…/dest/${x%.*}".*
  if [ $# -eq 1 ] && ! [ -e "$1" ]; then
    echo "$x has not been converted"
  elif [ $# -gt 1 ]; then
    echo "$x has been converted to more than one output file: " "$@"
  else
    echo "$x has been converted to $1"
  fi
done

You should take a look at rdiff-backup it does rsync underneath, but with the additional intelligence that you require (and it makes incremental backups capable of rolling back, but you can configure to switch that off).

The latest release is old (2009), but that is a sign of stability.