.bash_profile

export PATH="$HOME/erlang/current/bin:$PATH"

erlcur() {
    DIR=`ls -lr $HOME/erlang | awk '/current/ { print $NF }'`
    echo -n ${DIR##*/}
}

erlsw() {
    TARGET=`find $HOME/erlang -depth 1 -type d -name "*$1*" | head -1`
    if [ -z "$TARGET" ]; then
        echo "No release matching $1\!"
        if [ -e $HOME/erlang/current ]; then
            echo Using `erlcur`
        fi
        return
    fi
    ln -nfs $TARGET $HOME/erlang/current
    echo Using `erlcur`
}

_erlbuild() {
    set -e
    RELNAME=$1
    shift
    EXTRACONFIGS=$@
    ORIGDIR=`pwd`
    TARBALL="otp_src_$RELNAME.tar.gz"
    BUILDDIR="otp_src_$RELNAME"
    PREFIX="$HOME/erlang/$RELNAME"
    if [[ ! -d "$PREFIX" ]]; then
        mkdir -p $HOME/erlang/_builds
        cd $HOME/erlang/_builds
        if [[ ! -f "$TARBALL" ]]; then
            echo -n "Downloading $RELNAME: "
            wget --progress=dot:mega https://packages.erlang-solutions.com/erlang/esl-erlang-src/$TARBALL
        fi
        if [[ ! -d $BUILDDIR ]]; then
            echo "Unpacking $RELNAME..."
            tar xzf $TARBALL
        fi
        cd $BUILDDIR
        echo "Configuring $RELNAME..."
        ./configure --prefix=$PREFIX --enable-darwin-64-bit --with-dynamic-trace=dtrace --disable-hipe $EXTRACONFIGS > /dev/null 2>&1
        touch lib/wx/SKIP
        echo "Building and installing $RELNAME into $PREFIX..."
        make all docs install install-docs > /dev/null 2>&1
        cd $ORIGDIR
    else
        echo "$RELNAME is already installed in $PREFIX"
        exit 1
    fi
}

erlbuild() {
    echo "_erlbuild $@" | $SHELL -l
}

erlclean() {
    RELNAME=$1
    echo "Removing build artifacts for $RELNAME:"
    rm -rvf $HOME/erlang/_builds/*$RELNAME*
}

Does this pre-suppose a directory set up of ~/elrang/$VERSION? where there is a directory for each version you want to switch to?

Yes.

Y no kerl? :)

@dizzyd kerl has caused so many hours of pain and annoyance.