Ruby Debugger Commands

ruby-debugger.md

Commands

Control flow

• s[tep]
  • Step in. Resume the program until next breakable point.
• s[tep] <n>
  • Step in, resume the program at <n>th breakable point.
• n[ext]
  • Step over. Resume the program until next line.
• n[ext] <n>
  • Step over, same as step <n>.
• fin[ish]
  • Finish this frame. Resume the program until the current frame is finished.
• fin[ish] <n>
  • Finish <n>th frames.
• c[ontinue]
  • Resume the program.
• q[uit] or Ctrl-D
  • Finish debugger (with the debuggee process on non-remote debugging).
• q[uit]!
  • Same as q[uit] but without the confirmation prompt.
• kill
  • Stop the debuggee process with Kernel#exit!.
• kill!
  • Same as kill but without the confirmation prompt.
• sigint
  • Execute SIGINT handler registered by the debuggee.
  • Note that this command should be used just after stop by SIGINT.

Breakpoint

• b[reak]
  • Show all breakpoints.
• b[reak] <line>
  • Set breakpoint on <line> at the current frame's file.
• b[reak] <file>:<line> or <file> <line>
  • Set breakpoint on <file>:<line>.
• b[reak] <class>#<name>
  • Set breakpoint on the method <class>#<name>.
• b[reak] <expr>.<name>
  • Set breakpoint on the method <expr>.<name>.
• b[reak] ... if: <expr>
  • break if <expr> is true at specified location.
• b[reak] ... pre: <command>
  • break and run <command> before stopping.
• b[reak] ... do: <command>
  • break and run <command>, and continue.
• b[reak] ... path: <path>
  • break if the path matches to <path>. <path> can be a regexp with /regexp/.
• b[reak] if: <expr>
  • break if: <expr> is true at any lines.
  • Note that this feature is super slow.
• catch <Error>
  • Set breakpoint on raising <Error>.
• catch ... if: <expr>
  • stops only if <expr> is true as well.
• catch ... pre: <command>
  • runs <command> before stopping.
• catch ... do: <command>
  • stops and run <command>, and continue.
• catch ... path: <path>
  • stops if the exception is raised from a <path>. <path> can be a regexp with /regexp/.
• watch @ivar
  • Stop the execution when the result of current scope's @ivar is changed.
  • Note that this feature is super slow.
• watch ... if: <expr>
  • stops only if <expr> is true as well.
• watch ... pre: <command>
  • runs <command> before stopping.
• watch ... do: <command>
  • stops and run <command>, and continue.
• watch ... path: <path>
  • stops if the path matches <path>. <path> can be a regexp with /regexp/.
• del[ete]
  • delete all breakpoints.
• del[ete] <bpnum>
  • delete specified breakpoint.

Information

• bt or backtrace
  • Show backtrace (frame) information.
• bt <num> or backtrace <num>
  • Only shows first <num> frames.
• bt /regexp/ or backtrace /regexp/
  • Only shows frames with method name or location info that matches /regexp/.
• bt <num> /regexp/ or backtrace <num> /regexp/
  • Only shows first <num> frames with method name or location info that matches /regexp/.
• l[ist]
  • Show current frame's source code.
  • Next list command shows the successor lines.
• l[ist] -
  • Show predecessor lines as opposed to the list command.
• l[ist] <start> or l[ist] <start>-<end>
  • Show current frame's source code from the line to if given.
• edit
  • Open the current file on the editor (use EDITOR environment variable).
  • Note that edited file will not be reloaded.
• edit <file>
  • Open on the editor.
• i[nfo]
  • Show information about current frame (local/instance variables and defined constants).
• i[nfo] l[ocal[s]]
  • Show information about the current frame (local variables)
  • It includes self as %self and a return value as %return.
• i[nfo] i[var[s]] or i[nfo] instance
  • Show information about instance variables about self.
• i[nfo] c[onst[s]] or i[nfo] constant[s]
  • Show information about accessible constants except toplevel constants.
• i[nfo] g[lobal[s]]
  • Show information about global variables
• i[nfo] ... /regexp/
  • Filter the output with /regexp/.
• i[nfo] th[read[s]]
  • Show all threads (same as th[read]).
• o[utline] or ls
  • Show you available methods, constants, local variables, and instance variables in the current scope.
• o[utline] <expr> or ls <expr>
  • Show you available methods and instance variables of the given object.
  • If the object is a class/module, it also lists its constants.
• display
  • Show display setting.
• display <expr>
  • Show the result of <expr> at every suspended timing.
• undisplay
  • Remove all display settings.
• undisplay <displaynum>
  • Remove a specified display setting.

Frame control

• f[rame]
  • Show the current frame.
• f[rame] <framenum>
  • Specify a current frame. Evaluation are run on specified frame.
• up
  • Specify the upper frame.
• down
  • Specify the lower frame.

Evaluate

• p <expr>
  • Evaluate like p <expr> on the current frame.
• pp <expr>
  • Evaluate like pp <expr> on the current frame.
• eval <expr>
  • Evaluate <expr> on the current frame.
• irb
  • Invoke irb on the current frame.

Trace

• trace
  • Show available tracers list.
• trace line
  • Add a line tracer. It indicates line events.
• trace call
  • Add a call tracer. It indicate call/return events.
• trace exception
  • Add an exception tracer. It indicates raising exceptions.
• trace object <expr>
  • Add an object tracer. It indicates that an object by <expr> is passed as a parameter or a receiver on method call.
• trace ... /regexp/
  • Indicates only matched events to /regexp/.
• trace ... into: <file>
  • Save trace information into: <file>.
• trace off <num>
  • Disable tracer specified by <num> (use trace command to check the numbers).
• trace off [line|call|pass]
  • Disable all tracers. If <type> is provided, disable specified type tracers.
• record
  • Show recording status.
• record [on|off]
  • Start/Stop recording.
• step back
  • Start replay. Step back with the last execution log.
  • s[tep] does stepping forward with the last log.
• step reset
  • Stop replay .

Thread control

• th[read]
  • Show all threads.
• th[read] <thnum>
  • Switch thread specified by <thnum>.

Configuration

• config
  • Show all configuration with description.
• config <name>
  • Show current configuration of .
• config set <name> <val> or config <name> = <val>
  • Set to .
• config append <name> <val> or config <name> << <val>
  • Append <val> to <name> if it is an array.
• config unset <name>
  • Set to default.
• source <file>
  • Evaluate lines in <file> as debug commands.
• open
  • open debuggee port on UNIX domain socket and wait for attaching.
  • Note that open command is EXPERIMENTAL.
• open [<host>:]<port>
  • open debuggee port on TCP/IP with given [<host>:]<port> and wait for attaching.
• open vscode
  • open debuggee port for VSCode and launch VSCode if available.
• open chrome
  • open debuggee port for Chrome and wait for attaching.

Help

• h[elp]
  • Show help for all commands.
• h[elp] <command>
  • Show help for the given command.