ssh-copykey

#!/bin/bash
#
# Will read key from ~/.ssh/id_*.pub by default.
# Use with '-s' option to read key from stdin.
# Use with '-i' to specify an ident to use to establish the connection

print_syntax() {
    echo "Syntax $0 [-s -i <id_rsa>] username@hostname"
    exit 1
}

OPTIND=1
STDIN=0
IDENT=""
while getopts ":si:" opt; do
    case "$opt" in
        s) STDIN=1
        ;;
        i) IDENT="-i $OPTARG"
        ;;
        *) print_syntax
    esac
done
shift $((OPTIND - 1))

if [ -z $1 ]; then
    print_syntax
fi

if [ $STDIN -eq 1 ] ; then
    KEY=`cat /dev/stdin`
else

    declare -a keyfiles
    FILES=$HOME/.ssh/id_*.pub
    for f in $FILES
    do
        if [ -f $f ]; then
            keyfiles=("${keyfiles[@]}" "$f")
        fi
    done

    if [ ${#keyfiles[@]} -lt 1 ]; then

        echo "No ssh key found..."
        echo "create one with 'ssh-keygen'."
        exit
    elif [ ${#keyfiles[@]} -gt 1 ]; then

        echo "Multiple keys found, choose one:"
        select KEY in ${keyfiles[@]}
        do
            KEY=`cat $KEY`
            break
        done
    else
        KEY=`cat ${keyfiles[0]}`
    fi

fi

echo "Uploading ssh key to $1..."
ssh -q $IDENT $* "umask 0077; mkdir -p ~/.ssh ; echo "$KEY" >> ~/.ssh/authorized_keys"
echo "done!"