add install script and g_aliases source-able file

configure

@@ -0,0 +1,104 @@
+#!/usr/bin/env bash
+# He wrote this in BASH because he hates himself, apparently :(
+USAGE="Usage: ./configure [-g|--global] [-u|--uninstall] [-f|--force]"
+set -ue
+
+# === Configure Install === #
+INSTALL_PATH_HOME="$HOME/.local/bin"
+INSTALL_PATH_GLOBAL="/usr/local/bin"
+SCRIPT_PERM=555
+ALIASES_PERM=444
+# ========================= #
+
+# NOTE: since this last changed in 2015 its a really good unique identifier...
+# NOTE: (to avoid uninstalling other programs called g)
+G_IDENTIFIER="I'm writing this in BASH because I hate myself, apparently."
+
+# Filters filenames based on if the file contains the G_IDENTIFIER
+is_this_g() {
+  while read -r LOC; do
+    if [[ -d "$LOC" ]]; then
+      LOC="$LOC/g"
+    fi
+    grep -lF "$G_IDENTIFIER" "$LOC" 2>/dev/null
+  done <&0
+}
+
+# Finds absolute paths to all installed g binaries
+# (or the extremely rare case there are multiple)
+find_installed() {
+  (echo -e "$INSTALL_PATH_HOME\n$INSTALL_PATH_GLOBAL" && which -a g 2>/dev/null) \
+    | is_this_g
+  exit 0
+}
+
+# Escapes all / \ & characters in sed patterns
+escape_pattern() {
+  <<< "$1" sed -e 's/[\/&]/\\&/g'
+}
+
+install_g() {
+  local LOC=$1
+  local FORCE=$2
+  mkdir -p "$LOC"
+
+  FOUND=$(find_installed)
+  if [[ -n "$FOUND" && -z "$FORCE" ]]; then
+    echo "Failed: g already exists at:" $FOUND >&2
+    echo "   1. Run \`./configure --uninstall\` to remove, OR" >&2
+    echo "   2. Use \`--force\` to overwrite" >&2
+    exit 2
+  fi
+  
+  install -m "$SCRIPT_PERM" bin/g "$LOC/g"
+  install -m "$ALIASES_PERM" bin/g_aliases "$LOC/g_aliases"
+  # Format config strings for `g_aliases`
+  local G_BIN_DIR=$(escape_pattern "$LOC")
+  sed -i -e "s/AUTO_G_BIN_DIR/$G_BIN_DIR/g" "$LOC/g_aliases"
+  
+  echo "Installed bin/g -> $LOC/g"
+  echo "Installed bin/g_aliases -> $LOC/g_aliases"
+  echo -e "\n[+] To use the aliases, add this to your ~/.bashrc or ~/.bash_aliases:"
+  echo "### source $LOC/g_aliases"
+}
+
+uninstall_g() {
+  local FOUND=""
+  while read -r LOC; do
+    local FOUND="1"
+    LOC=$(dirname "$LOC")
+    rm "$LOC/g" "$LOC/g_aliases"
+    rmdir "$LOC"
+    echo "Removed: $LOC/g"
+    echo "Removed: $LOC/g_aliases"
+  done < <(find_installed | uniq -u)
+
+  if [[ -z "$FOUND" ]]; then
+    echo "Failed: g was not found to be installed" >&2
+    exit 2
+  fi
+
+  echo -e "\nAliases are still bound!\nUse \`source ~/.bashrc\` or \`exec \`$SHELL\`"
+}
+
+INSTALL_PATH="$INSTALL_PATH_HOME"
+FORCE=
+for OPT in "$@"; do
+  case $OPT in
+    -g|--global)
+      INSTALL_PATH="$INSTALL_PATH_GLOBAL"
+      ;;
+    -u|--uninstall)
+      uninstall_g
+      exit 0 # non-zero will already propagate from `set -e`
+      ;;
+    -f|--force)
+      FORCE="1"
+      ;;
+    *)
+      echo -e "Unknown option $OPT\n$USAGE" >&2
+      exit 1
+      ;;
+  esac
+done
+install_g "$INSTALL_PATH" "$FORCE"