Add update-dotfiles utility

.config/shell/env

@@ -8,7 +8,7 @@
 
 export XDG_CACHE_HOME="$HOME/.cache"
 export XDG_CONFIG_HOME="$HOME/.config"
-export XDG_DATA_HOME="$HOME/.local/share"  # also set in ~/.local/bin/{generate-shell-completions,install-dotfiles}
+export XDG_DATA_HOME="$HOME/.local/share"  # also set in ~/.local/bin/{generate-shell-completions,install-dotfiles,update-dotfiles}
 export XDG_STATE_HOME="$HOME/.local/state"  # also set in ~/.local/bin/generate-shell-completions
 
 # Make up a XDG directory for binaries (that does not exist in the standard)
@@ -17,7 +17,7 @@ export XDG_BIN_HOME="$HOME/.local/bin"  # also set in ~/.local/bin/install-dotfi
 
 # Convenient names for various places in the system
 
-export DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.local/bin/install-dotfiles
+export DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.local/bin/{install-dotfiles,update-dotfiles}
 
 
 # Generic shell configs

.local/bin/update-dotfiles

@@ -0,0 +1,83 @@
+#!/bin/sh
+
+# Replace the local `dotfiles` repository with a fresh install
+# by downloading and re-running the latest `install-dotfiles`
+#
+# Refuses to run if there are uncommitted or unpushed changes,
+# unless called with `--force`
+
+set -eu
+
+
+XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"  # also set in ~/.config/shell/env
+
+DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.config/shell/env
+
+INSTALLER_URL="https://code.webartifex.de/alexander/dotfiles/raw/branch/main/.local/bin/install-dotfiles"
+
+
+force=0
+[ "${1:-}" = "--force" ] && force=1
+
+
+_git() {
+    git --git-dir="$DOTFILES_DIR" --work-tree="$HOME" "$@"
+}
+
+
+branch="main"
+
+
+if [ -d "$DOTFILES_DIR" ]; then
+
+    # Keep the machine on its current branch (e.g., "desktop")
+    branch=$(_git symbolic-ref --short HEAD)
+
+    if [ "$force" -ne 1 ]; then
+
+        if [ -n "$(_git status --porcelain)" ]; then
+            echo ""
+            echo "There are uncommitted changes!" >&2
+            echo "" >&2
+            _git --no-pager diff HEAD --stat >&2
+            echo "" >&2
+            echo "=> Commit and push them, or re-run with --force" >&2
+            echo ""
+            exit 1
+        fi
+
+        if _git rev-parse --verify --quiet "origin/$branch" >/dev/null \
+            && [ -n "$(_git log --oneline "origin/$branch..$branch")" ]; then
+            echo ""
+            echo "There are unpushed commits!" >&2
+            echo "" >&2
+            _git --no-pager log --oneline "origin/$branch..$branch" >&2
+            echo "" >&2
+            echo "=> Push them, or re-run with --force" >&2
+            echo ""
+            exit 1
+        fi
+
+    fi
+
+fi
+
+
+installer=$(mktemp)
+trap 'rm -f "$installer"' EXIT
+
+
+if command -v curl >/dev/null 2>&1; then
+    curl -fsSL "$INSTALLER_URL" -o "$installer"
+elif command -v wget >/dev/null 2>&1; then
+    wget -q "$INSTALLER_URL" -O "$installer"
+else
+    echo ""
+    echo "Neither curl nor wget are installed!" >&2
+    echo "=> Install one of them" >&2
+    echo ""
+    exit 1
+fi
+
+
+DOTFILES_BRANCH="$branch" FORCE_INSTALL=1 sh "$installer"