The various standards dictate which header file must define each of the standard functions. This is the included header file documented with each function prototype in the Reference Section of this manual.

However, many of the functions defined by the standards already existed on several operating systems and were defined in different header files. This is especially true on OpenVMS systems with the header files <processes.h> , <unixio.h> , and <unixlib.h> .

So, to provide upward compatibility for these functions, their prototypes are duplicated in both the expected header file as well as the header file defined by the standards.

Table C-1 lists these functions.

Table C-1 Duplicated Prototypes

Function	Duplicated in	Standard says
access	<unixio.h>	<unistd.h>
alarm	<signal.h>	<unistd.h>
bcmp	<string.h>	<strings.h>
bcopy	<string.h>	<strings.h>
bzero	<string.h>	<strings.h>
chdir	<unixio.h>	<unistd.h>
chmod	<unixio.h>	<stat.h>
chown	<unixio.h>	<unistd.h>
close	<unixio.h>	<unistd.h>
creat	<unixio.h>	<fcntl.h>
ctermid	<stdio.h>	<unistd.h>
cuserid	<stdio.h>	<unistd.h>
dirname	<string.h>	<libgen.h>
dup	<unixio.h>	<unistd.h>
dup2	<unixio.h>	<unistd.h>
ecvt	<unixlib.h>	<stdlib.h>
execl	<processes.h>	<unistd.h>
execle	<processes.h>	<unistd.h>
execlp	<processes.h>	<unistd.h>
execv	<processes.h>	<unistd.h>
execve	<processes.h>	<unistd.h>
execvp	<processes.h>	<unistd.h>
_exit	<stdlib.h>	<unistd.h>
fcvt	<unixlib.h>	<stdlib.h>
ffs	<string.h>	<strings.h>
fsync	<stdio.h>	<unistd.h>
ftime	<time.h>	<timeb.h>
gcvt	<unixlib.h>	<stdlib.h>
getcwd	<unixlib.h>	<unistd.h>
getegid	<unixlib.h>	<unistd.h>
getenv	<unixlib.h>	<stdlib.h>
geteuid	<unixlib.h>	<unistd.h>
getgid	<unixlib.h>	<unistd.h>
getopt	<stdio.h>	<unistd.h>
getpid	<unixlib.h>	<unistd.h>
getppid	<unixlib.h>	<unistd.h>
getuid	<unixlib.h>	<unistd.h>
index	<string.h>	<strings.h>
isatty	<unixio.h>	<unistd.h>
lseek	<unixio.h>	<unistd.h>
mkdir	<unixlib.h>	<stat.h>
mktemp	<unixio.h>	<stdlib.h>
nice	<stdlib.h>	<unistd.h>
open	<unixio.h>	<fcntl.h>
pause	<signal.h>	<unistd.h>
pipe	<processes.h>	<unistd.h>
read	<unixio.h>	<unistd.h>
rindex	<string.h>	<strings.h>
sbrk	<stdlib.h>	<unistd.h>
setgid	<unixlib.h>	<unistd.h>
setuid	<unixlib.h>	<unistd.h>
sleep	<signal.h>	<unistd.h>
strcasecmp	<string.h>	<strings.h>
strncasecmp	<string.h>	<strings.h>
system	<processes.h>	<stdlib.h>
times	<time.h>	<times.h>
umask	<stdlib.h>	<stat.h>
vfork	<processes.h>	<unistd.h>
wait	<processes.h>	<wait.h>
write	<unixio.h>	<unistd.h>