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LLDB on CLI

1. Build with debug symbols
   • for spm
     • swift build -c debug -Xswiftc -g
2. run lldb ./path/to/exe
   • for spm, it'll be swift build followed by lldb .build/debug/<your exe name>
   • for spm tests, you can run lldb .build/debug/<YourPackageName>PackageTests.xctest
3. To set breakpoints
   • breakpoint set --file FileName.swift --line 42
4. run

Cheatsheet

Starting LLDB

• Launch LLDB with an executable:

  • lldb ./executable

• Attach to a running process by PID:

  • lldb -p <pid>
• Attach by process name:
  • lldb --attach-name <process-name>

Basic Commands

• Run the program:

  • run or r

• Continue execution:

  • continue or c

• Step over:

  • next or n

• Step into:

  • step or s
• Step out (finish the current function):
  • finish

Breakpoints

• Set a breakpoint by line number:

  • breakpoint set --file <file> --line <line-number>

• Set a breakpoint by function name:

  • breakpoint set --name <function-name>

• List all breakpoints:

  • breakpoint list
• Delete a breakpoint by ID:
  • breakpoint delete <breakpoint-id>

Inspection

• Print variable value:

  • print <variable-name> or p <variable-name>

• Examine memory:

  • memory read <address>

• Backtrace (stack trace):

  • bt or thread backtrace

• List local variables:

  • frame variable or fr v
• Format output (e.g., hexadecimal):
  • frame variable -f hex <variable-name> or p/x <variable-name>

Modifying Execution

• Set a variable's value:
  • expr <variable-name> = <value>

Navigation

• List source code:

  • list
• View disassembly:
  • disassemble or dis

Exiting LLDB

• Quit LLDB:
  • quit or exit

Useful Aliases

• Make your life simpler by setting these up in an .lldbinit file:

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  this document last modified: October 12 2024 18:42

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