lldb (with examples)

1: Debug an executable

To debug an executable using lldb, you simply need to provide the path to the executable as a command-line argument.

Code:

lldb executable

Motivation:

Debugging an executable is useful when you encounter issues or bugs in a program and want to investigate them further. By using lldb, you can step through the code, inspect variables, and examine the program state to understand what is happening at each step.

Explanation:

• lldb: The command to launch the LLVM Low-Level Debugger.
• executable: The path to the executable file you want to debug.

Example Output:

(lldb) target create "executable"
(lldb) b main
(lldb) r
...

In this example, lldb loads the executable and sets a breakpoint at the main function. After running the program, the debugger breaks at the first line of code in the main function.

2: Attach lldb to a running process with a given PID

Sometimes you may want to attach lldb to a process that is already running. This allows you to debug the program at a certain point in its execution.

Code:

lldb -p pid

Motivation:

Attaching lldb to a running process can be useful when you want to investigate issues in a long-running program or when you encounter a crash or unexpected behavior.

Explanation:

• lldb: The command to launch the LLVM Low-Level Debugger.
• -p pid: The -p option followed by the process ID (PID) of the running process you want to attach to.

Example Output:

Attaching to process with PID '12345'...

This attaches lldb to the process with the PID 12345. Once attached, you can start debugging the program and inspect its state.

3: Wait for a new process to launch with a given name and attach to it

In some scenarios, you may want to wait for a specific process to be launched and then attach lldb to it automatically.

Code:

lldb -w -n process_name

Motivation:

This use case is helpful when you want to debug a process that will be launched later or if you want to automate the debugging process for a specific application.

Explanation:

• lldb: The command to launch the LLVM Low-Level Debugger.
• -w: The -w option makes lldb wait until the process named process_name is launched.
• -n process_name: The -n option followed by the name of the process you want to attach to.

Example Output:

Waiting for process 'process_name' to launch...

This command waits for a process with the name process_name to be launched. Once the process is detected, lldb attaches to it, and you can start debugging.

By understanding the different use cases of the lldb command, you can effectively debug executables, attach to running processes, and automate the debugging process. These examples showcase how you can leverage lldb to investigate and resolve issues in your programs.