sdb − SNOBOL4 debugger
sdb [ options ... ] program.sno
sdb is a debugger for snobol4(1) programs, in the mold (clawning fone) of gdb(1), The GNU debugger. sdb(1) uses readline(3) for command line editing/history when available.
Commands:
break LABEL_OR_STATEMENT_NUMBER
Set a breakpoint.
bt
Display call stack backtrace.
commands BREAKPOINT_NUMBER
Add sdb commands to execute (ie; print & continue) to a breakpoint.
condition BREAKPOINT_NUMBER EXPR
If EXPR is supplied, it is used as a predicate to make the breakpoint conditional.
continue EMPTY_OR_COUNT
Continue from breakpoint. The optional count specifies how many times to continue past this breakpoint (sets "ignore" count).
delete BREAKPOINT_NUMBER_OR_EMPTY
Delete a single breakpoint, or all breakpoints.
disable BREAKPOINT_NUMBER_OR_EMPTY
Temporarily disable a breakpoint, or all breakpoints.
enable BREAKPOINT_NUMBER_OR_EMPTY
Reenable a breakpoint, or all breakpoints.
finish
Resume debugging after current function returns. Will display function return type and value, if any.
help
Display help.
ignore BREAKPOINT_NUMBER COUNT
Set breakpoint ignore count.
info
Display list of breakpoints and their status.
list EMPTY_OR_STATEMENT_NUMBER
Display source code.
next EMPTY_OR_COUNT
Single step execution, skipping over function calls.
print EXPRESSION
Evaluate expression and print result. Can be used to call functions, or set variables.
quit
Exit debugger.
step EMPTY_OR_COUNT
Single step.
watch VARIABLE
Set watchpoint on a variable (break when value changes).
what
Display the datatype of variable contents (or expression).
where
An alias for bt.
A blank line repeats the previous command.
Non-ambiguous abbreviations of commands can be used (ie; "s", "n").
The GNU Readline library (when available) will be used for sdb input for command editing and history.
The keyboard interrupt character (eg; Control C) will stop a running program and return control to the sdb(1) command prompt.
If your program calls the SDB() function, it will act as a breakpoint. You can check whether sdb(1) is loaded with the FUNCTION predicate, ie;
FUNCTION(’SDB’) SDB()
snobol4(1), gdb(1), readline(3), snobol4readline(3)
Philip L. Budne
Inspired by Fred Weigel’s DDT.SNO and SITBOL’s SNODDT.
sdb(1) uses a wide variety of system facilities and will interact poorly with any programs that use any number of features, including:
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Altering listing settings with directive/control lines. | ||
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Altering &STLIMIT, &ERRLIMIT, or &TRACE. | ||
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Calling SETEXIT() |
If you try to put a breakpoint on a label or line with no code or goto fields, the breakpoint will never be triggered.
You cannot put a breakpoint on the END label (however control always returns to sdb when the END label is reached).
There is no "run" command; you cannot restart the program without quitting and losing breakpoint settings.
Interrupt character trapping is in it’s infancy, and only occurs at the start of a each statement executed.
The interrupt character is silently ignored when at the sdb command prompt.
sdb does not read an init file (ie; .sdbinit).