Debugger in Ruby
ruby -rdebug
It is good to use it without any additional gem.
$ ruby -rdebug your_ruby.rb (rdb:1) h Debugger help v.-0.002b Commands b[reak] [file:|class:]<line|method> b[reak] [class.]<line|method> set breakpoint to some position wat[ch] <expression> set watchpoint to some expression cat[ch] (<exception>|off) set catchpoint to an exception b[reak] list breakpoints cat[ch] show catchpoint del[ete][ nnn] delete some or all breakpoints disp[lay] <expression> add expression into display expression list undisp[lay][ nnn] delete one particular or all display expressions c[ont] run until program ends or hit breakpoint s[tep][ nnn] step (into methods) one line or till line nnn n[ext][ nnn] go over one line or till line nnn w[here] display frames f[rame] alias for where l[ist][ (-|nn-mm)] list program, - lists backwards nn-mm lists given lines up[ nn] move to higher frame down[ nn] move to lower frame fin[ish] return to outer frame tr[ace] (on|off) set trace mode of current thread tr[ace] (on|off) all set trace mode of all threads q[uit] exit from debugger v[ar] g[lobal] show global variables v[ar] l[ocal] show local variables v[ar] i[nstance] <object> show instance variables of object v[ar] c[onst] <object> show constants of object m[ethod] i[nstance] <obj> show methods of object m[ethod] <class|module> show instance methods of class or module th[read] l[ist] list all threads th[read] c[ur[rent]] show current thread th[read] [sw[itch]] <nnn> switch thread context to nnn th[read] stop <nnn> stop thread nnn th[read] resume <nnn> resume thread nnn pp expression evaluate expression and pretty_print its value p expression evaluate expression and print its value r[estart] restart program h[elp] print this help <everything else> evaluate
