HP 3000 Manuals

System Debug Reference Manual

IF 

If condition evaluates to TRUE, then execute all commands in cmdlist,
else execute all commands in cmdlist2.

Syntax 

     IF condition THEN command 

     IF condition THEN { cmdlist }

     IF condition THEN   command1  ELSE command2 

     IF condition THEN { cmdlist } ELSE command2 

     IF condition THEN  command1   ELSE { cmdlist2 }

     IF condition THEN { cmdlist } ELSE { cmdlist2 }

Parameters 

condition        A logical expression to be evaluated.

command cmdlist  A single command (or command list) that is executed if
                 condition evaluates to TRUE.

command2         A single command (or command list) that is executed if
cmdlist2         condition evaluates to FALSE.

Note that in nested IF-THEN-ELSE clauses, the first ELSE clause always 
matches the first IF clause.  This is different from the conventions of
most compilers, and it may not be intuitive.  Explicit use of {cmdlists} 
is recommended in these nested cases.

Examples 

     %cmdebug > if [q-3]>[db+4] then c 

If the contents of Q-3 are greater than the contents of DB+4, then
continue.

     $nmdebug > if (length>20) and (pcsf=a) then {wl "GOT IT"; c} 

If the value of the variable length is greater than 20, and the contents
of the predefined variable pcsf equals $a, then execute the following
from the command list:  print the string "GOT IT", then continue.

     $nmdat > if 1 then {if 0 then wl "wee" else wl "willy"} else wl "wonka" 
     willy

This example shows a nested IF-THEN-ELSE clause within a cmdlist clause.

Limitations, Restrictions 

The interpreter does not parse or analyze the contents of the clauses
prior to their execution.  Based on the value of the condition, the THEN
or ELSE clause is be executed, and the other clause disregarded.

This implies that the clauses may be syntactically illegal, but the
errors are not discovered until they are executed.

Note that in the following examples, entire clauses are bogus, but not
detected:

     $nmdebug > if TRUE then wl "good" else XXXXXXXXXXXXXXXXXX 
     good

     $nmdebug > if FALSE then XXXXXXXXXXXXXXXX else wl "good" 
     good


CAUTION  The output format of all System Debug commands is subject to
         change without notice.  Programs that are developed to
         postprocess System Debug output should not depend on the exact
         format (spacing, alignment, number of lines, uppercase or
         lowercase, or spelling) of any System Debug command output.

MPE/iX 5.0 Documentation