Byebug Cheatsheet - organized by related commands

byebug_commands.md

Byebug Cheatsheet

This cheatsheet includes most of the byebug commands organized by related commands (e.g. breakpoint related commands are together).

To see official help...

Command	Aliases	Example	Comments
help	h	h	list top level of all commands
help cmd	h cmd-alias	h n	list the details of a command (example shows requesting details for the next command) (this works for all commands)

Stepping through code

Command	Aliases	Example	Comments
next	n	n	step over to next line in same block or method (or back to calling block/method if at end of current block/method)
		n 3	step over next N lines (e.g. if on line 11, n 3 will continue and break on line 14)
step	s	s	step into block or method
		s 3	step in 3 times
continue	c	c	continue execution to next breakpoint (or end of program if no breakpoints reached)
		c 43	continues and stops at line 43 (stopping at breakpoint if encountered first)
continue!	c!	c!	continue execution to end of program ignoring all breakpoints

Breakpoint Commands

Command	Aliases	Example	Comments
info breakpoints	i b	i b	Lists breakpoint id, enabled?, and breakpoint line
break	b	b 33	Set breakpoint at specified line (e.g. 33) in the current file
disable breakpoint	dis b	dis b 2	Disable breakpoint with id (e.g. 2) (disables all if no id specified)
enable breakpoint	en b	en b 2	Enable breakpoint with id (e.g. 2) (disables all if no id specified)
delete	del	del 1	Deletes breakpoint with id (e.g. 1) (deletes all if no id specified)
condition	cond	cond 3 i > 3	Breaks at breakpoint with id (e.g. 3) only if condition is met
		cond 3	Removes condition from breakpoint with id (e.g. 3)

Watch Commands

Enabled watch expressions display every time byebug stops.

Command	Aliases	Example	Comments
info display	i d	i d	Lists display id, enabled?, and expression being watched
display	disp	disp arg	Set expression to watch (e.g. arg) everytime the debugger stops
		disp	Lists all display expressions with values
disable display	dis d	dis d 2	Disable display with id (e.g. 2) (maybe - disables all if no id specified)
enable display	en d	en d 2	Enable display with id (e.g. 2) (maybe - enables all if no id specified)
undisplay	undisp	undisp 1	Stop displaying expression with id (e.g. 1) (stops displaying all if no id specified)

Variable values

Command	Aliases	Example	Comments
var args	v a	v a	show arguments and values for current method
var local	v l	v l	show local variable and values for current scope (e.g. scope = method or block)
var instance	v i	v i	show instance variables and values for instance
		v i obj	show instance variables and values for another object (e.g. obj)
var const	v c	v c	show constants and values for current instance's class
		v c klass	show constants and values for another module/class (e.g. klass)
var global	v g	v g	show global variables and values
var all	v all	v all	show local, global, and instance variables and values of self

Tracing and Location

Command	Aliases	Example	Comments
list=	l=	l=	List 5 before and 4 after the current line pending execution (resets to current stop point)
list	l	l 8-20	List specified range of lines (e.g. lines 8-20)
		l	List next 10 lines from current location listed. (l again gives next 10 after that)
list-	l-	l-	List previous 10 lines from current location listed. (l- again gives previous 10 before that)
where or backtrace	w or bt	w	display backtrace (w and bt are the same command)
		bt	display backtrace