At any time when the debugger waits for your input the command h prints a help screen.
#h
h help
s step one line, or just press return on the line
S step one line, do not step into functions or subs
o step until getting out of the current function
(if you stepped into but changed your mind)
? var print the value of a variable
u step one level up in the stack
d step one level down in the stack (for variable printing)
D step down in the stack to current execution depth
G list all global variables
L list all local variables
l [n-m] list the source lines
r [n] run to line n
R [n] run to line n but do not stop in recursive function call
b [n] set breakpoint on the line n or the current line
B [n-m] remove breakpoints from lines
q quit the program
#_