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From: Wolfram Schneider <wosch@cs.tu-berlin.de>
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Date: Mon, 14 Aug 1995 18:54:50 +0200
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To: Garrett Wollman <wollman@halloran-eldar.lcs.mit.edu>
Cc: current@freebsd.org
Subject: make(1) extension for SHELL COMMANDS
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Garrett Wollman writes:
>> Note: the following example don't use /bin/sh in BSD make, our make
>>       use execv(3)
>
>Well, that's yet another way in which pmake is broken with respect to
>POSIX.  I'm not at all surprised to hear it.  We don't need to make
>the situation even worse than it already is.

FYI: GNU-make use a similar algorithm 
(first exec and if errno=ENOEXEC SHELL).


$ uname -rs
SunOS 5.4

$ make -v
GNU Make version 3.70, by Richard Stallman and Roland McGrath.
Copyright (C) 1988, 89, 90, 91, 92, 93 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.


1. with /bin/sh

$ cat Makefile 
date:
        date "+%D <>"

$ truss -fo /tmp/truss make
date "+%D <>"
08/14/95 <>

$ egrep  'fork|exec' /tmp/truss 
10625:  execve("/usr/local/zib_bin/make", 0xEFFFF810, 0xEFFFF818)  argc = 1
10625:  fork()                                          = 10626
10626:  fork()          (returning as child ...)        = 10625
10626:  execve("/bin/sh", 0x00057E98, 0x00057CF8)  argc = 3
10626:  fork()                                          = 10628
10628:  fork()          (returning as child ...)        = 10626
10628:  execve("/usr/bin/date", 0x00036470, 0x00036538)  argc = 2



2. without /bin/sh (no meta chars)

$ cat Makefile 
date:
        date

$ truss -fo /tmp/truss make
date
Mon Aug 14 18:28:50 MET DST 1995

$ egrep  'fork|exec' /tmp/truss 
10641:  execve("/usr/local/zib_bin/make", 0xEFFFF810, 0xEFFFF818)  argc = 1
10641:  fork()                                          = 10642
10642:  fork()          (returning as child ...)        = 10641
10642:  execve("/usr/bin/date", 0x0004FE50, 0x00057CF8)  argc = 1




$ more make-3.74/job.c

/* Replace the current process with one running the command in ARGV,
   with environment ENVP.  This function does not return.  */

void
exec_command (argv, envp)
     char **argv, **envp;
{
  /* Be the user, permanently.  */
  child_access ();

  /* Run the program.  */
  environ = envp;
  execvp (argv[0], argv);
  
  switch (errno)
    {
    case ENOENT:
      error ("%s: Command not found", argv[0]);
      break;
    case ENOEXEC:
      {
	/* The file is not executable.  Try it as a shell script.  */
	extern char *getenv ();
	char *shell;
	char **new_argv;
	int argc;

	shell = getenv ("SHELL");