#include <unistd.h> int execvp(const char *path, char *const argv[]);
exec
functions,
execvp
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 execvp
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.
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.
execvp
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 execvp
is unsuccessful.
execvp
to execute the ls
shell command:
#include <sys/types.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> main() { pid_t pid; char *const parmList[] = {"/bin/ls", "-l", "/u/userid/dirname", NULL}; if ((pid = fork()) == -1) perror("fork() error"); else if (pid == 0) { execvp("ls", parmList); printf("Return not expected. Must be an execvp() error.n"); } }
execlp
,
execv