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execlp |
Portability: | POSIX.1 conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
EXAMPLE | |
RELATED FUNCTIONS |
SYNOPSIS |
#include <unistd.h> int execlp(const char *path, const char *arg0, ..., NULL);
DESCRIPTION |
Like all of the
exec
functions,
execlp
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
execlp
function is most commonly used to overlay a process image that
has been created by a call to the
fork
function.
path
path
argument contains a slash (
/
), it is assumed that either an absolute or
a relative pathname has been specified. If the
path
argument does not contain a slash, the directories specified by
the
PATH
environment variable
are searched in an attempt to locate the 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.
RETURN VALUE |
A successful call to
execlp
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
execlp
is unsuccessful.
EXAMPLE |
The following example illustrates creating
a new process and executing an HFS file called
newShell
. The path
/u/userid/bin
is added at the end of the
PATH
environment variable before calling
execlp
.
Note:
You must specify the
posix
option when compiling this
example.
#include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <stdlib.h> main() { pid_t pid; char *pathvar; char newpath[1000]; pathvar = getenv("PATH"); strcpy(newpath, pathvar); strcat(newpath, ":u/userid/bin"); setenv("PATH", newpath); if ((pid = fork()) == -1) perror("fork error"); else if (pid == 0) { execlp("newShell", "newShell", NULL); printf("Return not expected. Must be an execlp error.\\n"); } }
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Copyright © 2001 by SAS Institute Inc., Cary, NC, USA. All rights reserved.