Chapter Contents |
Previous |
Next |
execve |
Portability: | POSIX.1 conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
EXAMPLE | |
SEE ALSO |
SYNOPSIS |
#include <unistd.h> int execve(const char *file, char *const argv[], char *const envp[]);
DESCRIPTION |
Like all of the
exec
functions,
execve
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
execve
function is most commonly used to overlay a process image that
has been created by a call to the
fork
function.
file
argv
NULL
pointer is used to mark the end of the array. Each character string
pointed to by the array is used to pass an argument to the new process image.
The first argument,
argv[0]
,
is required and must contain the name of the executable file for the new process
image.
envp
NULL
pointer is used to mark the end of the array. Each character string
pointed to by the array is used to pass an environment variable to the new
process image.
RETURN VALUE |
A successful call to
execve
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
execve
is unsuccessful.
EXAMPLE |
The following example illustrates the
use of
execve
to execute
the
ls
shell command. Notice
that the
STEPLIB
environment
variable is set for the new process.
#include <sys/types.h> #include <unistd.h> #include <stdio.h> main() { pid_t pid; char *const parmList[] = {"/bin/ls", "-l", "/u/userid/dirname", NULL\}; char *const envParms[2] = {"STEPLIB=SASC.V6.LINKLIB", NULL\}; if ((pid = fork()) ==-1) perror("fork error"); else if (pid == 0) { execve("/u/userid/bin/newShell", parmList, envParms); printf("Return not expected. Must be an execve error.\\n"); } }
SEE ALSO |
Chapter Contents |
Previous |
Next |
Top of Page |
Copyright © 2001 by SAS Institute Inc., Cary, NC, USA. All rights reserved.