in reply to How can I print variable contents from the debugger non-interactively?

Hi davehorner,

It seems to me that the answers you've received so far may probably be more complicated than what you actually wanted to know.

To print the content of a scalar variable $var, simply issue the following commands at the debugger prompt:

p $var
Sometimes it is better to put some special characters around the variable in order to see possible invisible characters:
p "<$var>"
To see the content of a non scalar variable such as an array or a hash, use the x command:
x @array
or use a reference to the variable for a clearer output:
x \%hash;
And remember you can always issue the h command at the debugger prompt to get some help:
DB<1> h List/search source lines: Control script execution: l [ln|sub] List source code T Stack trace - or . List previous/current line s [expr] Single step [in +expr] v [line] View around line n [expr] Next, steps over + subs f filename View source in file <CR/Enter> Repeat last n or + s /pattern/ ?patt? Search forw/backw r Return from subr +outine M Show module versions c [ln|sub] Continue until p +osition Debugger controls: L List break/watch +/actions o [...] Set debugger options t [expr] Toggle trace [tr +ace expr] <[<]|{[{]|>[>] [cmd] Do pre/post-prompt b [ln|event|sub] [cnd] Set b +reakpoint ! [N|pat] Redo a previous command B ln|* Delete a/all bre +akpoints H [-num] Display last num commands a [ln] cmd Do cmd before li +ne = [a val] Define/list an alias A ln|* Delete a/all act +ions h [db_cmd] Get help on command w expr Add a watch expr +ession h h Complete help page W expr|* Delete a/all wat +ch exprs |[|]db_cmd Send output to pager ![!] syscmd Run cmd in a sub +process q or ^D Quit R Attempt a restar +t Data Examination: expr Execute perl code, also see: s,n,t expr x|m expr Evals expr in list context, dumps the result or lists + methods. p expr Print expression (uses script's current package). S [[!]pat] List subroutine names [not] matching pattern V [Pk [Vars]] List Variables in Package. Vars can be ~pattern or ! +pattern. X [Vars] Same as "V current_package [Vars]". i class inherita +nce tree. y [n [Vars]] List lexicals in higher scope <n>. Vars same as V. e Display thread id E Display all thread ids. For more help, type h cmd_letter, or run man perldebug for all docs.

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Re^2: How can I print variable contents from the debugger non-interactively?
by LanX (Saint) on Jul 15, 2017 at 09:14 UTC
    Well he said "non-interactively" , but yeah he might mean it differently.

    Cheers Rolf
    (addicted to the Perl Programming Language and ☆☆☆☆ :)
    Je suis Charlie!

      Oops, yes I missed that (I probably failed to read the title).

      Update: I wonder why someone would want to use the debugger non-interactively. I can't think of cases where this would be useful.

        Thank you LanX for your replies, I did mean using the debugger non-interactively (i.e. using environment variables/cmdline args to tell the debugger which variables should be printed when executed non-interactively).

        Laurent_R thank you for your reply detailing some ways of printing variables from the interactive debugger, if you would like additional description of a case which might require non-interactive debugger usage please read the update within the original question.