Add base configuration

- Follow XDG standard: ~/.config and ~/.local folders
- Set environment variables and define aliases within ~/.config/shell
- Add installation script for easy setup
- Add README.md with info on the installation and general notes

.local/bin/README.md

@@ -0,0 +1,3 @@
+# User-local Executables
+
+This folder contains executable files that are on the `$PATH`.

.local/bin/install-dotfiles

@@ -0,0 +1,91 @@
+#!/bin/sh
+
+# Installation script to make the dotfiles available in ~/
+#
+# `git` is the only dependency for this script to run (See: https://git-scm.com)
+#
+# See: https://code.webartifex.biz/alexander/dotfiles#installation
+
+
+set -eu
+
+
+XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"  # also set in ~/.config/shell/env
+
+DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.config/shell/env
+
+# Defaults to the minimal/server version on the "main" branch
+# => Set DOTFILES_BRANCH=desktop explicitly when installing on a desktop machine
+DOTFILES_BRANCH="${DOTFILES_BRANCH:-main}"
+
+DOTFILES_HTTPS="https://code.webartifex.biz/alexander/dotfiles"
+DOTFILES_SSH="git@git.webartifex.biz:alexander/dotfiles.git"
+
+BACKUP_DIR="$HOME/.dotfiles-backup-$(date +%Y%m%d-%H%M%S)"
+
+
+if [ -d "$DOTFILES_DIR" ]; then
+
+    if [ "${FORCE_INSTALL:-}" != "1" ]; then
+        echo ""
+        echo "The dotfiles are already installed at: $DOTFILES_DIR"
+        echo ""
+        echo "Options:"
+        echo "  - Set 'export FORCE_INSTALL=1' and run installation again"
+        echo "  - Update with 'dotfiles pull' and continue using them"
+        echo ""
+
+        exit 0
+    fi
+
+    echo "Backing up the existing repository to: $BACKUP_DIR"
+    mkdir -p "$BACKUP_DIR"
+    mv "$DOTFILES_DIR" "$BACKUP_DIR/dotfiles"
+
+fi
+
+
+git clone --bare "$DOTFILES_HTTPS" "$DOTFILES_DIR"
+
+
+_git() {
+    git --git-dir="$DOTFILES_DIR" --work-tree="$HOME" "$@"
+}
+
+
+if ! _git show-ref --verify --quiet "refs/heads/$DOTFILES_BRANCH"; then
+    echo ""
+    echo "Branch '$DOTFILES_BRANCH' does not exist in the repository"
+    echo ""
+    echo "Available branches:"
+    _git branch --format='  %(refname:short)'
+    echo ""
+
+    exit 1
+fi
+
+
+# Do not checkout project documentation intended for web GUIs
+_git config core.sparseCheckout true
+{
+    echo "/*"
+    echo "!LICENSE.txt"
+    echo "!README.md"
+} > "$DOTFILES_DIR/info/sparse-checkout"
+
+# Put the dotfiles in the user's $HOME folder
+_git checkout --force "$DOTFILES_BRANCH"
+
+# Do not show files not tracked in the dotfiles repository because there are simply too many
+_git config --local status.showUntrackedFiles no
+
+# Prefer `ssh` for syncing between the machines
+_git remote set-url origin "$DOTFILES_SSH"
+
+
+echo ""
+echo "The dotfiles were installed successfully (branch: $DOTFILES_BRANCH)"
+echo ""
+echo "Reload your shell to start using them:"
+echo "    exec \$SHELL -l"
+echo ""