Add 'k3os/set_hostname.sh'

k3os/set_hostname.sh

@@ -0,0 +1,67 @@
+#!/bin/bash
+
+# Script to set the hostname in the k3os config.yaml file using only standard tools (sed, grep).
+
+# Define the path to the config file
+CONFIG_FILE="/k3os/system/config.yaml"
+
+# --- Function to get user input ---
+get_hostname_input() {
+    # Loop until a non-empty hostname is provided
+    while true; do
+        read -r -p "Enter the desired new hostname: " NEW_HOSTNAME
+        if [ -n "$NEW_HOSTNAME" ]; then
+            break
+        else
+            echo "Error: Hostname cannot be empty. Please enter a valid name."
+        fi
+    done
+}
+
+# --- Function to modify the config file ---
+set_hostname() {
+    local NEW_HOSTNAME="$1"
+    # Note the two spaces for YAML indentation under 'k3os:'
+    local HOSTNAME_ENTRY="  hostname: $NEW_HOSTNAME" 
+
+    echo "Attempting to set hostname to: **$NEW_HOSTNAME** in **$CONFIG_FILE**"
+
+    # 1. Check if the 'k3os:' block exists
+    if ! grep -q "^k3os:" "$CONFIG_FILE"; then
+        echo "'k3os:' block not found. Appending the block and hostname."
+        # Append the k3os block and the new hostname entry
+        echo -e "\nk3os:\n$HOSTNAME_ENTRY" >> "$CONFIG_FILE"
+    
+    # 2. Check if a 'hostname' entry already exists under 'k3os:'
+    # Checks for the 'k3os:' block AND an indented 'hostname:' line
+    elif grep -q "^k3os:" "$CONFIG_FILE" && grep -q "^\s\+hostname:" "$CONFIG_FILE"; then
+        echo "Existing hostname found. Replacing the entry."
+        # Use sed to replace the existing hostname line under k3os
+        # /^\s*hostname:/ matches any line starting with optional spaces followed by 'hostname:'
+        sed -i "/^\s*hostname:/c\\$HOSTNAME_ENTRY" "$CONFIG_FILE"
+        
+    # 3. 'k3os:' exists but 'hostname:' does not.
+    else
+        echo "'k3os:' block found, but no hostname entry. Appending the entry."
+        # Use sed to insert the new hostname entry immediately after the 'k3os:' line
+        # The 'a\' command appends text after the matched line
+        sed -i "/^k3os:/a\\$HOSTNAME_ENTRY" "$CONFIG_FILE"
+    fi
+
+    # Check the exit status of the previous command
+    if [ $? -eq 0 ]; then
+        echo "Successfully updated the hostname in $CONFIG_FILE."
+        echo "The change will take effect after a reboot."
+        echo ""
+        echo "--- Verification (Hostname line only) ---"
+        # Print the modified line for verification
+        grep -E "^\s*hostname:" "$CONFIG_FILE"
+    else
+        echo "Failed to modify $CONFIG_FILE."
+        exit 1
+    fi
+}
+
+# --- Main execution ---
+get_hostname_input
+set_hostname "$NEW_HOSTNAME"