Add skeleton code

README.md

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+# PiDP 10 Services
+
+## Overview
+
+This repository combines a set of useful scripts and services, to run on the
+PiDP-10 in order to make it easier to work with it and develop for it. These
+services can be installed on the PiDP-10 and automate tasks such as copying
+files onto the ITS operating system. These tools help automate processes, that
+would require interaction with the Linux part of the PiDP-10 when developing on
+another system.
+
+## git-monitor
+
+The git-monitor is a system service, that monitors a target directory on the
+PiDP-10. It contains a file with a list of git repositories to monitor, one at a
+time. The service will check if any of the repositories changed, and pull them.
+After a successful pull a script will be called, if it exists, that allows the
+newly updated repository to interact with a running PDP-10 simulation.
+
+The monitor consists of a script, that needs to be installed to `/usr/local/bin`
+and a systemd unit-file to run it as a service.

services/git-monitor

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+#!/bin/bash
+
+# Configuration (Customize these!)
+REPO_URL="ssh://gitea@git.orca-central.de:10229/jali/PDP10Sudoku.git"
+REPO_LOCAL_PATH="/home/jali/Projects/PDP10Sudoku"
+BRANCH_NAME="develop"
+POLL_INTERVAL=60  # Seconds between checks
+#LOG_FILE="/var/log/git-monitor.log" # Log file for recording actions
+LOCK_FILE="/tmp/git-monitor.lock" # File to prevent multiple instances running concurrently
+
+# Functions
+log_message() {
+  local level=$1
+  local message=$2
+  timestamp=$(date +'%Y-%m-%d %H:%M:%S')
+  #echo "$timestamp [$level] $message" >> "$LOG_FILE"
+  echo "$timestamp [$level] $message"  # Also print to console (optional)
+}
+
+check_lock() {
+  if [ -f "$LOCK_FILE" ]; then
+    log_message "WARN" "Another instance is already running. Exiting."
+    exit 1
+  fi
+}
+
+create_lock() {
+  touch "$LOCK_FILE"
+}
+
+remove_lock() {
+  rm -f "$LOCK_FILE"
+}
+
+initialize_repo() {
+  if [ ! -d "$REPO_LOCAL_PATH" ]; then
+    log_message "INFO" "Repository directory does not exist. Cloning..."
+    mkdir -p "$REPO_LOCAL_PATH"
+    git clone --depth 1 "$REPO_URL" "$REPO_LOCAL_PATH"
+    if [ $? -ne 0 ]; then
+      log_message "ERROR" "Failed to clone repository. Exiting."
+      exit 1
+    fi
+    log_message "INFO" "Repository cloned successfully."
+  fi
+}
+
+check_for_updates() {
+  local last_commit_hash
+  local current_commit_hash
+
+  # Get the last known commit hash (from a file)
+  if [ -f "$REPO_LOCAL_PATH/.git-monitor-last-commit" ]; then
+    last_commit_hash=$(cat "$REPO_LOCAL_PATH/.git-monitor-last-commit")
+  else
+    last_commit_hash="" # Initialize if file doesn't exist
+  fi
+
+  # Fetch the latest commit hash from the remote repository
+  current_commit_hash=$(git -C "$REPO_LOCAL_PATH" branch --format '%(sha)')
+
+  if [ -z "$last_commit_hash" ] || [ "$current_commit_hash" != "$last_commit_hash" ]; then
+    log_message "INFO" "New commits detected. Pulling..."
+    git -C "$REPO_LOCAL_PATH" pull origin "$BRANCH_NAME"
+    if [ $? -eq 0 ]; then
+      log_message "INFO" "Pull successful."
+
+      # Update the last commit hash file
+      echo "$current_commit_hash" > "$REPO_LOCAL_PATH/.git-monitor-last-commit"
+    else
+      log_message "ERROR" "Pull failed."
+    fi
+  fi
+}
+
+# Main Execution
+check_lock
+create_lock
+
+log_message "INFO" "Git monitor started."
+
+initialize_repo
+
+while true; do
+  check_for_updates
+  sleep "$POLL_INTERVAL"
+done
+
+remove_lock # This won't be reached in this infinite loop.  Useful if exiting gracefully.