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NOTE

1.2 GCC

Install GCC on Windows/MSYS2 and record common GDB debugging commands.

Developer ToolsUpdated 2 min readhistorical

This is a historical learning note and may contain outdated or incomplete understanding.

1. Installation

1.1. Install MSYS2

msys2.md

1.2. Install GCC

For the current MSYS2 UCRT64 environment, install the matching toolchain:

pacman -Syu
pacman -S --needed mingw-w64-ucrt-x86_64-toolchain mingw-w64-ucrt-x86_64-gdb

The old pacman -S base-devel gcc gdb command targets the MSYS environment itself. For native Windows programs, use the toolchain packages for the selected environment.

2. GDB

2.1. Running

  • run / r: run the program and stop at breakpoints.
  • continue / c: continue until the next breakpoint or program exit.
  • next / n: step without normally entering a called function.
  • step / s: step into a debuggable called function.
  • until: continue to a later source location; commonly useful for getting past loops. Exact behavior depends on the current location and arguments.
  • until LINE: run to a specified source location.
  • finish: run until the current function returns.
  • call function(args): call a visible function in the debugging context.
  • quit / q: exit GDB.

2.2. Breakpoints

  • break n / b n: break at line n.
  • break file.cpp:578: break at a file and line.
  • break fn1 if a > b: conditional breakpoint.
  • break func: break at a function entry.
  • delete n, disable n, enable n: manage a breakpoint.
  • clear n: clear a source-line breakpoint.
  • info breakpoints / info b: list breakpoints.
  • delete breakpoints: remove all breakpoints.

2.3. Viewing Source

  • list / l: list source.
  • list LINE: show source around a line.
  • list FUNCTION: show source around a function.
  • Repeating list continues with later source lines.

2.4. Printing Expressions

  • print EXPR / p EXPR: evaluate and print an expression.
  • print ++a: evaluate and print while also changing program state.
  • display EXPR: display an expression whenever execution stops.
  • watch EXPR: set a watchpoint; availability depends on the platform.
  • whatis: query a type.
  • info functions: list functions.
  • info locals: show locals.

2.5. Runtime Information

  • where / bt / backtrace: show the call stack.
  • up / down: move between stack frames.
  • set args: set program arguments.
  • show args: show arguments.
  • info program: show execution state and stop reason.

3. References