what

packages/plow/package.nix

@@ -0,0 +1,6 @@
+{writeShellApplication}:
+writeShellApplication {
+  name = "plow";
+
+  text = builtins.readFile ./plow.bash;
+}

packages/plow/plow.bash

@@ -0,0 +1,120 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+progname="$0"
+
+error() {
+    local line
+    for line in "$@"; do
+        echo "$progname: $line" 1>&2
+    done
+
+    exit 1
+}
+
+shopt -s nullglob globstar
+
+if [[ ! -v PLOW_CACHE || -z $PLOW_CACHE ]]; then
+    PLOW_CACHE=.plowcache
+fi
+
+args=$(
+    getopt \
+        --options f:t:Fivm: \
+        --longoptions from:,to:,force,interactive,verbose,directory-mode: \
+        --name "$0" \
+        -- "$@"
+)
+
+eval set -- "$args"
+
+from=${PLOW_FROM:-$PWD}
+to=${PLOW_TO:-$HOME}
+lnflags=()
+mkdirflags=()
+rmflags=()
+while true; do
+    case "$1" in
+    -f | --from)
+        from=$2
+        shift 2
+        ;;
+    -t | --to)
+        to=$2
+        shift 2
+        ;;
+    -F | --force)
+        lnflags+=(--force)
+        rmflags+=(--force)
+        shift
+        ;;
+    -i | --interactive)
+        lnflags+=(--interactive)
+        rmflags+=(--interactive)
+        shift
+        ;;
+    -v | --verbose)
+        lnflags+=(--verbose)
+        mkdirflags+=(--verbose)
+        rmflags+=(--verbose)
+        shift
+        ;;
+    -m | --directory-mode)
+        mkdirflags+=(--mode "$2")
+        shift 2
+        ;;
+    --)
+        shift
+        break
+        ;;
+    esac
+done
+
+from=$(realpath --strip -- "$from")
+to=$(realpath --strip -- "$to")
+
+if (($# > 0)); then
+    choices=("$@")
+else
+    choices=()
+    for dir in "$from"/*/; do
+        choices+=("$(basename -- "$dir")")
+    done
+fi
+
+shopt -s dotglob
+
+cache=()
+if [[ -n $PLOW_CACHE ]]; then
+    if [[ -r $PLOW_CACHE ]]; then
+        while IFS= read -r link; do
+            cache+=("$link")
+        done <"$PLOW_CACHE"
+    fi
+
+    : >"$PLOW_CACHE"
+fi
+
+for choice in "${choices[@]}"; do
+    prefix=$from/$choice
+    for target in "$prefix"/**/*; do
+        if [[ -f $target ]]; then
+            link=$to${target#"$prefix"}
+            parent=$(dirname -- "$link")
+            mkdir --parents "${mkdirflags[@]}" -- "$parent"
+            ln --symbolic "${lnflags[@]}" -- "$target" "$link"
+            if [[ -n "$PLOW_CACHE" ]]; then
+                echo "$link" >>"$PLOW_CACHE"
+            fi
+        fi
+    done
+done
+
+for link in "${cache[@]}"; do
+    if [[ -L "$link" && ! -f "$link" ]]; then
+        rm "${rmflags[@]}" -- "$link"
+    fi
+done