Some command_processor_ pipes don't work in subsystem request lines. Others do.

[Gary Dixon]

Inside an SSU subsystem like analyze_multics (azm), a request line using pipe syntax is supposed to
return the output of an azm request line as results of a pipe-capturing active request string. Using azm
as an example:

azm

azm:  sld >dumps>gary_dumps>3
  ERF 3   in directory >dumps>gary_dumps dumped at 08/21/23  1019.4 pdt Mon.
  System-ID MR12.8 Version-ID MR12.8
Proc   0 DBR  17171450 running        on cpu a   Initializer.SysDaemon.z

azm:  d 234 -as stack_header.ect_ptr;
  ect_ptr = 340|16040 >pdd>!zzzzzzzbBBBBBB>!BBBKWznZHhplJH.area.linker|16040


azm:  sbag &1 ||[d 234 -as stack_header.ect_ptr;|]
azm: File does not exist.

azm:  sbag &1 "  ect_ptr = 340|16040 >pdd>!zzzzzzzbBBBBBB>!BBBKWznZHhplJH.area.linker|16040"
  ect_ptr = 340|16040 >pdd>!zzzzzzzbBBBBBB>!BBBKWznZHhplJH.area.linker|16040

azm:  

An equivalent set of commands does work at Multics command level. For example:

dump_segment 234 -as stack_header.ect_ptr
000000
  ect_ptr = 247|17240   [pd]>!BBBKXCDgBLglMZ.area.linker
r 11:27 0.172 0

string ||[dump_segment 234 -as stack_header.ect_ptr;|]
000000   ect_ptr = 247|17240   [pd]>!BBBKXCDgBLglMZ.area.linker
r 11:28 0.237 2

[Gary Dixon]

It appears this symptom falls under the class of limitations described by a comment at the top of command_processor_.pl1 source program.

%page;
/*  LIMITATIONS AN KNOWN BUGS:  */

/*  1)  Nested iteration sets will not return the expected results.

        example:

        string (xxx_(a b) (c d)_yyy zzz)

        intermixes the inner interation set.

    2)  The pipe processing code cannot deal with pipes that are
        embedded as part of an active return string.

        examples:

        string "show;|cols";| xx
        ls;| [contents xx;|]

        string [[ioa_ "string (ab a bc cd ae ef);|match /a/";|]]

        Because the pipe code evaluates the command line as it is input,
        the value returned by the active string will not be diagnosed
        correctly as a pipe.
*/        

Limitation 2 encompasses the symptoms of this bug.