In case you have a complex program and you want to debug only a certain part of it you need break points.
The command b sets a so called breakpoint at the line for which the line serial number is given. Issue the commands:
-----------------------------------------------------
001. print "hello\n"
002. a = 3
003.
004. sub MyFunction(t)
005. local a,b,c
006.
007. b = t + 2
* 008. print b
009. print " ",t
010. if t > 1 then MyFunction t-1
* 011. print " *"
012. end sub
013.
014. MyFunction a
015.
>016. a = a + 2
017.
018. MyFunction a
-----------------------------------------------------
#_
#b8
done
#b11
done
#l -
As you can see in the listing the lines are preceded by a * character. When the program is executed using the command r (or even R) the execution will stop when it reaches one of the break points.
Because many times programmers want to set a breakpoint on the actual line, if you issue the command b without argument it will set the breakpoint on the actual line.
-----------------------------------------------------
006.
007. b = t + 2
*>008. print b
009. print " ",t
010. if t > 1 then MyFunction t-1
-----------------------------------------------------
#_
#R
To remove the breakpoints you should issue the command B. The command B n removes the breakpoint from the line n. The command b n-m removes all breakpoints that are on the lines from n to line m including the line n and line m. Both n and m are optional. For example B - removes all breakpoints.