SVN post commit: Who is the user that committed?

Using the svnlook command with author. For example, in a shell script, it might be:

REPOS="$1"
REV="$2"

AUTHOR="$(svnlook author -r $REV $REPOS)"

post-commit hook script example:

#!/bin/sh
REPOS="$1"
REV="$2"
AUTHOR="$(svnlook author $REPOS -r $REV)"

# output on STDERR will be marshalled back to SVN client
echo "This transaction was commited by '$AUTHOR'!" 1>&2

exit 0