Push (skyv) Pull (trekk) to global directory stack file, but keep only one

push_pull.zsh

# Functions that push and pull to a singleton working directory...a bare-bones pushd/popd.
# For namespace clartiy, Norwegian words were use: skyv (push) and trekk (pull).
# Adapted from here https://stackoverflow.com/a/9916812

directory_stack=$HOME/.directory_singleton
function skyv() {
    # Save only one skyv path, overwriting the last
    echo $(pwd) > $directory_stack
}

function trekk() {
    # Pulls the skyv path, but leaves it there
    [ ! -s $directory_stack ] && return
    newdir=$(sed -n '$p' $directory_stack)
    cd $newdir
}