#include <unistd.h> int execl(const char *file, const char *arg0, ..., NULL);
exec
functions,
execl
replaces the calling process image with a new process
image. This has the effect of running a new program with the process
ID of the calling process. Note that a new process is not started;
the new process image simply overlays the original process image.
The execl
function is most commonly used to overlay a
process image that has been created by a call to the fork
function.
file
arg0, ..., NULL
NULL
pointer. The first argument,
arg0
, is required and must contain the name of the executable
file for the new process image. If the new process image is a
normal SAS/C
main
program, the list of arguments will be passed to
argv
as a pointer to an array of strings. The number of
strings in the array is passed to the main()
function as
argc
.
ARG_MAX
specifies the maximum number of bytes, including the
NULL
terminator at the end of the string, that can
be passed as arguments to the new process image.
The value of ARG_MAX
is obtained
by calling the sysconf
function with the _SC_ARG_MAX
symbol.
execl
does not have a return value
because the new process image overlays the calling process image.
However,
a -1
is returned if the call to execl
is unsuccessful.
newShell
:
#include <sys/types.h> #include <unistd.h> #include <stdio.h> main() { pid_t pid; if ((pid = fork()) == -1) perror("fork error"); else if (pid == 0) { execl("/u/userid/bin/newShell", "newShell", NULL); printf("Return not expected. Must be an execl() error.n"); } }
execle
, execlp
, execv
Copyright (c) 1998 SAS Institute Inc. Cary, NC, USA. All rights reserved.