Re: Ada Equivalent of "system()" in C?

[dewar@cs.nyu.edu (Robert Dewar)]

Dave Emery said

"The Unix function system() is not included in POSIX.1 or POSIX.5.  I
believe that it is included in the POSIX.1a revision that is still in
development."

However, it *is* in fact in the ANSI C standard, although the semantics
are pretty much entirely implementation defined.

In general the Ada standard library avoids functions that cannot be
well defined in a portable manner, although, to be honest, the command
line interface is pretty much in this category already.

Anyway, Peter's recipe for interfacing to C is certainly one approach.

If you are using GNAT, you could also use GNAT.OS_Lib.Spawn. Spawn is
a routine in the GNAT supplied predefined package GNAT.OS_Lib which has
a handful of useful operating systems interfaces (it is the interface
used by the GNAT compiler itself). Here is the documentatoin from the
spec:

   procedure Spawn
     (Program_Name : String;
      Args         : Argument_List;
      Success      : out Boolean);
   --  The first parameter of function Spawn is the full path name of the
   --  executable. The second parameter contains the arguments to be passed
   --  to the program. Success is false if the program could not be spawned
   --  or its execution completed unsuccessfully. Note that the caller will
   --  be blocked until the execution of the spawned program is complete.