diff --git a/aider/commands.py b/aider/commands.py
index eae6b8a89..a17b57edb 100644
--- a/aider/commands.py
+++ b/aider/commands.py
@@ -333,6 +333,7 @@ class Commands:
 
     def cmd_run(self, args):
         "Run a shell command and optionally add the output to the chat"
+        combined_output = None
         try:
             parsed_args = shlex.split(args)
             result = subprocess.run(
@@ -342,6 +343,9 @@ class Commands:
         except Exception as e:
             self.io.tool_error(f"Error running command: {e}")
 
+        if combined_output is None:
+            return
+
         self.io.tool_output(combined_output)
 
         if self.io.confirm_ask("Add the output to the chat?", default="y"):
diff --git a/aider/io.py b/aider/io.py
index 086813b61..dee90b78f 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -148,6 +148,7 @@ class InputOutput:
             return
         except UnicodeError as e:
             self.tool_error(f"{filename}: {e}")
+            self.tool_error("Use --encoding to set the unicode encoding.")
             return
 
     def write_text(self, filename, content):
diff --git a/docs/install.md b/docs/install.md
index c607d7da6..0389a0ba4 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -75,9 +75,9 @@ You should consult the
 for official instructions on how to install it in your environment.
 But you may be able to install a compatible version using these commands:
 
-* Mac: `brew install universal-ctags`
+* Mac: `brew update && brew install universal-ctags`
 * Windows: `choco install universal-ctags`
-* Ubuntu: `sudo apt-get install universal-ctags`
+* Ubuntu: `sudo apt update && sudo apt install universal-ctags`
 
 You know aider has found a working ctags if you see this output when you launch aider: