Installation guide

The POSIX-conformant definition of getpgrp on DIGITAL UNIX
systems states that getpgrp is called without arguments and returns
the process group of the current process:
pid_t = getpgrp();
The ULTRIX system’s mechanism for setting a process’s group ID is:
void = setpgrp(int, int);
This system call is supported on DIGITAL UNIX systems for
compatibility only. In new applications, use the POSIX-standard
setgpid call:
pid_t = setpgid(pid_t, pid_t);
• On ULTRIX systems, read operations on directories are supported by
the following statements:
#include <sys/dir.h>
struct direct *readdir(dirp);
DIR *dirp;
On DIGITAL UNIX systems, read operations on directories are
supported by the following statements:
#include <sys/dirent.h>
struct dirent *readdir(DIR *dirp);
See opendir
(3) for more information.
• On DIGITAL UNIX systems, the setsysinfo and getsysinfo system
calls have been expanded to provide unaligned access control similar to
that found on ULTRIX systems. In addition, SSI_UACPROC and
SSI_UACPARNT options accept three other options as arguments:
– UAC_NOPRINT
Suppresses the printing of the unaligned error message to the user.
– UAC_NOFIX
Instructs the operating system not to fix the unaligned access fault.
– UAC_SIGBUS
Forces a SIGBUS signal to be delivered to the thread.
These options are defined in sys/proc.h, and can be specified in any
combination on a per task basis.
UAC settings are inherited by children, so forked processes will have the
same UAC characteristics as their parent. The SSI_UACSYS option only
accepts the UAC_NOPRINT option and suppresses unaligned fixup
messages regardless of the users’ setting. Only the superuser is allowed
to use this option.
The following example shows the setsysinfo call usage in an
application:
7–42 Migrating Your ULTRIX Application to a DIGITAL UNIX System