Git commit-msg hook to check for maximum line lengths

.git_hooks_commit-msg

#!/bin/sh
#
# .git/hooks/commit-msg
#
# Check for maximum line lengths
#
# A git hook script to check the commit log message.
# Called by "git commit" with one argument, the name of the file
# that has the commit message.  The hook should exit with non-zero
# status after issuing an appropriate message if it wants to stop the
# commit.
#
cat "$1" | head -1 | grep -e '^..\{50\}' >/dev/null && {
        echo >&2 "First line exceeds 50 char limit."
        exit 1
}
cat "$1" | head -2 | tail -1 | grep -e '^\S*$' 2>/dev/null ||
        echo >&2 "Second line must be empty."
        exit 1
}
cat "$1" | tail -n +2 | grep -e '^..\{72\}' >/dev/null && {
        echo >&2 "Line exceeds 72 char limit."
        exit 1
}

Nice. Are you using this?