Digital UNIX Diffs - exec(5) Digital UNIX Diffs - exec(5)NAME
exec, execl, execle, execlp, execv, execve, execvp - Executes a file
LIBRARY
Standard C Library (libc.a): execlp(), execvp()SYNOPSIS
#include <unistd.h> extern char ∗∗environ; int execl (
const char ∗path,
const char ∗arg,
... ); int execv (
const char ∗path,
char ∗ const argv[ ] );
int execle (
const char ∗path,
const char ∗arg,
...
char ∗ const envp[ ] );
int execve (
const char ∗path,
char ∗ const argv[ ],
char ∗ const envp[ ] );
int execlp (
const char ∗file,
const char ∗arg,
... );
int execvp (
const char ∗file,
char ∗ const argv[ ] );
PARAMETERS
Points to a pathname identifying the new process image file. Specifies
a pointer to a null-terminated string. Specifies an array of character
pointers to null-terminated strings, constituting the environment for
the new process. Identifies the new process image file.
DIFFERENCESvms-process(5): OpenVMS Process Model Differences
exec(2) functions used in conjunction with vfork(2) on OpenVMS simu‐
lates vfork(2) or fork(2) used with an exec function on Digital UNIX.
The pair of functions create and initialize a new process running a new
image. On UNIX, fork creates a new process running the same image.
exec then causes a process to run another image. On OpenVMS, vfork
prepares to run a new program while an exec function starts a new
process running a new program.
The characteristics of the newly created process also differs between
the 2 operating systems. Whereas the process created by the UNIX fork
is identical to its parent, on OpenVMS the newly created process only
shares some of its parent characteristics. Characteristics passed to
the child on OpenVMS include: parent's umask, open filenames and posi‐
tions, SIG_IGN signal actions (not SIG_DFL), environment variables, and
argument vectors. The list of inherited attributes on UNIX are listed
in fork(2).
exec(2) functions on OpenVMS are limited to using images created by DEC
C since they rely on special initialization routines to enable UNIX
like process communication not normally used by processes on OpenVMS.
vms-files(5): OpenVMS File System Differences
The syntax of image file path or file is different on UNIX and OpenVMS.
RELATED INFORMATION
Functions: vfork(2), execl(2)CATEGORY INDEXvms-process(5), vms-files(5)
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Digital UNIX Diffs - exec(5)