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explain_execvp(3)	   Library Functions Manual	     explain_execvp(3)

NAME
       explain_execvp -	explain	execvp(3) errors

SYNOPSIS
       #include	<libexplain/execvp.h>
       const char *explain_execvp(const	char *pathname,	char *const *argv);
       const char *explain_errno_execvp(int errnum, const char *pathname, char
       *const *argv);
       void explain_message_execvp(char	*message, int message_size, const char
       *pathname, char *const *argv);
       void  explain_message_errno_execvp(char *message, int message_size, int
       errnum, const char *pathname, char *const *argv);

DESCRIPTION
       These functions may be used to obtain explanations for errors  returned
       by the execvp(3)	system call.

   explain_execvp
       const char *explain_execvp(const	char *pathname,	char *const *argv);

       The  explain_execvp function is used to obtain an explanation of	an er-
       ror returned by the execvp(3) system call.  The least the message  will
       contain	is  the	 value of strerror(errno), but usually it will do much
       better, and indicate the	underlying cause in more detail.

       The errno global	variable will be used to obtain	the error value	to  be
       decoded.

       This  function  is intended to be used in a fashion similar to the fol-
       lowing example:
	      if (execvp(pathname, argv) < 0)
	      {
		  fprintf(stderr, "%s\n", explain_execvp(pathname, argv));
		  exit(EXIT_FAILURE);
	      }

       The above code example is available  pre-packaged  as  the  explain_ex-
       ecvp_or_die(3) function.

       pathname
	       The  original pathname, exactly as passed to the	execvp(3) sys-
	       tem call.

       argv    The original argv, exactly as passed to	the  execvp(3)	system
	       call.

       Returns:
	       The  message  explaining	 the  error.   This  message buffer is
	       shared by all libexplain	functions which	do not supply a	buffer
	       in  their  argument list.  This will be overwritten by the next
	       call to any libexplain function which shares this  buffer,  in-
	       cluding other threads.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

   explain_errno_execvp
       const char *explain_errno_execvp(int errnum, const char *pathname, char
       *const *argv);

       The  explain_errno_execvp  function is used to obtain an	explanation of
       an error	returned by the	execvp(3) system call.	The least the  message
       will  contain  is the value of strerror(errnum),	but usually it will do
       much better, and	indicate the underlying	cause in more detail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (execvp(pathname, argv) < 0)
	      {
		  int err = errno;
		  fprintf(stderr, "%s\n", explain_errno_execvp(err,
		      pathname,	argv));
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is available pre-packaged as the explain_ex-
       ecvp_or_die(3) function.

       errnum  The error value to be decoded, usually obtained from the	 errno
	       global  variable	 just before this function is called.  This is
	       necessary if you	need to	call any code between the system  call
	       to  be explained	and this function, because many	libc functions
	       will alter the value of errno.

       pathname
	       The original pathname, exactly as passed	to the execvp(3)  sys-
	       tem call.

       argv    The  original  argv,  exactly as	passed to the execvp(3)	system
	       call.

       Returns:
	       The message explaining  the  error.   This  message  buffer  is
	       shared by all libexplain	functions which	do not supply a	buffer
	       in their	argument list.	This will be overwritten by  the  next
	       call  to	 any libexplain	function which shares this buffer, in-
	       cluding other threads.

       Note: This function is not thread safe, because it shares a return buf-
       fer across all threads, and many	other functions	in this	library.

   explain_message_execvp
       void explain_message_execvp(char	*message, int message_size, const char
       *pathname, char *const *argv);

       The explain_message_execvp function may be used to  obtain an  explana-
       tion  of	an error returned by the execvp(3) system call.	 The least the
       message will contain is the value of strerror(errno),  but  usually  it
       will do much better, and	indicate the underlying	cause in more detail.

       The  errno global variable will be used to obtain the error value to be
       decoded.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (execvp(pathname, argv) < 0)
	      {
		  char message[3000];
		  explain_message_execvp(message, sizeof(message), pathname, argv);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is available pre-packaged as the explain_ex-
       ecvp_or_die(3) function.

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 message  return  buffer is supplied, this function is
	       thread safe.

       message_size
	       The size	in bytes of the	location in which  to  store  the  re-
	       turned message.

       pathname
	       The  original pathname, exactly as passed to the	execvp(3) sys-
	       tem call.

       argv    The original argv, exactly as passed to	the  execvp(3)	system
	       call.

   explain_message_errno_execvp
       void  explain_message_errno_execvp(char *message, int message_size, int
       errnum, const char *pathname, char *const *argv);

       The explain_message_errno_execvp	function may be	used to	obtain an  ex-
       planation of an error returned by the execvp(3) system call.  The least
       the message will	contain	is the value of	strerror(errnum), but  usually
       it  will	 do much better, and indicate the underlying cause in more de-
       tail.

       This function is	intended to be used in a fashion similar to  the  fol-
       lowing example:
	      if (execvp(pathname, argv) < 0)
	      {
		  int err = errno;
		  char message[3000];
		  explain_message_errno_execvp(message,	sizeof(message),
		      err, pathname, argv);
		  fprintf(stderr, "%s\n", message);
		  exit(EXIT_FAILURE);
	      }

       The  above  code	 example  is available pre-packaged as the explain_ex-
       ecvp_or_die(3) function.

       message The location in which to	store  the  returned  message.	 If  a
	       suitable	 message  return  buffer is supplied, this function is
	       thread safe.

       message_size
	       The size	in bytes of the	location in which  to  store  the  re-
	       turned message.

       errnum  The  error value	to be decoded, usually obtained	from the errno
	       global variable just before this	function is called.   This  is
	       necessary  if you need to call any code between the system call
	       to be explained and this	function, because many libc  functions
	       will alter the value of errno.

       pathname
	       The  original pathname, exactly as passed to the	execvp(3) sys-
	       tem call.

       argv    The original argv, exactly as passed to	the  execvp(3)	system
	       call.

SEE ALSO
       execvp(3)
	       execute a file

       explain_execvp_or_die(3)
	       execute a file and report errors

COPYRIGHT
       libexplain version 1.3
       Copyright (C) 2009 Peter	Miller

							     explain_execvp(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | COPYRIGHT

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