mirror of
https://github.com/GnoConsortium/gno.git
synced 2024-11-18 19:09:31 +00:00
82 lines
1.6 KiB
Groff
82 lines
1.6 KiB
Groff
|
.\"
|
||
|
|
.\" $Id: exec.3,v 1.1 1997/02/27 07:32:22 gdr Exp $
|
||
|
|
.\"
|
||
|
|
.TH EXEC 3 "19 January 1997" GNO "Library Routines"
|
||
|
|
.SH NAME
|
||
|
|
.BR exec
|
||
|
|
\- load an executable file and launch as a new process
|
||
|
|
.SH SYNOPSIS
|
||
|
|
#include <unistd.h>
|
||
|
|
.sp 1
|
||
|
|
int
|
||
|
|
\fBexec\fR(const char *\fIpathname\fR, const char *\fIcmdline\fR);
|
||
|
|
.SH DESCRIPTION
|
||
|
|
This call is provided only for backward compatibility and should be
|
||
|
|
avoided. New programs should use the
|
||
|
|
.BR execve (2)
|
||
|
|
family of calls, the
|
||
|
|
.BR system (3)
|
||
|
|
routine, or the
|
||
|
|
.BR EXECUTE
|
||
|
|
shell call.
|
||
|
|
.LP
|
||
|
|
.BR exec
|
||
|
|
is an alternative method for launching a new process under GNO.
|
||
|
|
It is a combination of the
|
||
|
|
.BR fork (2)
|
||
|
|
and
|
||
|
|
.BR _execve (2)
|
||
|
|
system calls, and is in fact written in terms of them. The difference
|
||
|
|
between
|
||
|
|
.BR exec
|
||
|
|
and
|
||
|
|
.BR _execve
|
||
|
|
is that
|
||
|
|
.BR exec
|
||
|
|
returns in all cases; it is a simplified interface for those who don't
|
||
|
|
need to affect process information before a new executable begins
|
||
|
|
(such as process group IDs or I/O redirection information).
|
||
|
|
.LP
|
||
|
|
The (somewhat simplified) algorithm for
|
||
|
|
.BR exec
|
||
|
|
is as follows:
|
||
|
|
.RS
|
||
|
|
.nf
|
||
|
|
|
||
|
|
void exec2() {
|
||
|
|
return _execve();
|
||
|
|
}
|
||
|
|
int exec() {
|
||
|
|
return fork(exec2);
|
||
|
|
}
|
||
|
|
.fi
|
||
|
|
.RE
|
||
|
|
.SH RETURN VALUE
|
||
|
|
.BR exec
|
||
|
|
returns the process ID of the child, or -1 (and setting
|
||
|
|
.BR errno )
|
||
|
|
if an error occurs in either the
|
||
|
|
.BR fork
|
||
|
|
or
|
||
|
|
.BR _execve
|
||
|
|
call.
|
||
|
|
.SH BUGS
|
||
|
|
See the BUGS section in the
|
||
|
|
.BR execve (2)
|
||
|
|
man page.
|
||
|
|
.LP
|
||
|
|
If an error occurs in the
|
||
|
|
.BR _execve
|
||
|
|
phase of this call, it can only be detected with the
|
||
|
|
.BR wait (2)
|
||
|
|
system call; it will get the return code of the process, which will be -1
|
||
|
|
if the
|
||
|
|
.BR _execve
|
||
|
|
fails.
|
||
|
|
.SH SEE ALSO
|
||
|
|
.BR execve (2),
|
||
|
|
.BR fork (2),
|
||
|
|
.BR wait (2),
|
||
|
|
.BR execl (3),
|
||
|
|
.BR system (3).
|