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SDB(1)				CSNOBOL4 Manual				SDB(1)

NAME
       sdb - SNOBOL4 debugger

SYNOPSIS
       sdb [ options ... ] program.sno

DESCRIPTION
       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 back trace.

       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, if no EXPR is supplied, any previous
	   condition is	removed.

       continue	[ COUNT	]
	   Continue from breakpoint.  The optional count specifies how many
	   times to continue past this breakpoint (sets	ignore count).

       delete [	BREAKPOINT_NUMBER ]
	   Delete a single breakpoint, or all breakpoints.

       disable [ BREAKPOINT_NUMBER ]
	   Temporarily disable a breakpoint, or	all breakpoints.

       enable [	BREAKPOINT_NUMBER ]
	   Re-enable 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 (or clear) breakpoint ignore count.

       info
	   Display list	of breakpoints and their status.

       list [ LABEL_OR_STATEMENT_NUMBER	]
	   Display source code.

       next [ 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.

       run
	   Restart program (works by saving breakpoints	and restarting
	   snobol4).  New in version 2.1, some restrictions may	apply.

       save FILENAME
	   Save	breakpoints to file.

       source FILENAME
	   Read	sdb commands from file.

       step [ COUNT ]
	   Single step.

       watch VARIABLE
	   Set watchpoint on a variable	(break when value changes).

       what EXPRESSION
	   Display the datatype	of 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(1) 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()

FILES
       ~/.sdbinit
	   initial command file, read on startup.

       .sdb_history
	   saved command history

       /tmp/sdb_listing.pid
	   temporary listing file for sdb.sno to read

       /tmp/sdb_bkpts.pid
	   temporary breakpoint	save file for "run" command

SEE ALSO
       snobol4(1), gdb(1), readline(3),	snobol4readline(3)

AUTHOR
       Philip L. Budne

       Inspired	by Fred	Weigel's DDT.SNO and SITBOL's SNODDT.

LIMITATIONS
       sdb(1) uses a wide variety of system facilities and will	interact
       poorly with any programs	that use any number of features, including:

       o      Altering listing settings	with directive/control lines.

       o      Altering &STLIMIT, &ERRLIMIT, or &TRACE.

       o      Calling SETEXIT()

BUGS
       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).

       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.

       Leaves an unprotected listing file of the sources in the	/tmp directory
       (create a protected directory?).

       "quit" and "run"	commands say program is	running	even if	first line of
       the program has not yet been executed!

       Some fatal errors cannot	be trapped, and	sdb will be terminated.

CSNOBOL4B 2.1.6			August 9, 2020				SDB(1)

NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | AUTHOR | LIMITATIONS | BUGS

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