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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 [ 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.

       step [ 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(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()

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).

       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).

CSNOBOL4B 2.0                   January 1, 2015                         SDB(1)