install.sh

#! /bin/bash
# Process substitution

show_syntax() {
    printf "usage: ./%s < -y ~/bin/ | --skipped >\n
 -s | --skipped
        List files not installed

 -y     Write symlinks (ln -snv) into the specified directory.\n
 -yS    Install (only) the scary \"read it before running\" shortcuts.\n

This isn't so much an install, as placing the files the author likes
on \$PATH the way he does it.\n
It is ideminpotent: it will not overwrite existing files or links.\n
After the first install, the install destination is remembered and
can be omitted to install additional files.\n" \
    "$( basename $0 )"
}

do_inst() {
    local src dest instand leaf
    dest="$1"
    instand="$2"
    if [ -z "$dest" ]; then
	dest="$( git config plumbed-in-from.PATH )"
	if [ -z "$dest" ]; then
	    show_syntax
	    exit 1
	fi
	dest="$( dirname "$dest" )"
	echo "Using previous install directory $dest"
    fi
    src="$PWD"
    if ! [ -d "$dest" ] || ! [ -w "$dest" ]; then
	echo "$0: $dest is not a writable directory" >&2
	return 2
    fi

    ln -snv "$src/bin" "$dest/,git-yacontrib"
    git config plumbed-in-from.PATH "$dest/,git-yacontrib" # my suggested convention
    for leaf in $( cat "$src/$instand" ); do
	ln -snv ",git-yacontrib/$leaf" "$dest"
    done
}

show_skipped() {
    local src
    src="$PWD"
    diff -u \
	<( LC_ALL=C sort "$src"/install*.txt ) \
	<( find bin -type f -printf "%f\n" | LC_ALL=C sort )
}

unset CDPATH
cd "$( dirname "$0" )"
case "$1" in
    -y) do_inst "$2" install.txt ;;
    -yS) do_inst "$2" install-scary.txt ;;
#    -h | --help)
    -s|--skipped) show_skipped ;;
    *) show_syntax ;;
esac