POSIX_SINGLE_PROCESS

POSIX Single Process option group. More...

Files
file	confstr.h
	POSIX configuration string constants (<sys/confstr.h>)
file	sysconf.h
	POSIX runtime system configuration (<sys/sysconf.h>)
file	utsname.h
	POSIX system name identification (<sys/utsname.h>)

Functions
int	setenv (const char *envname, const char *envval, int overwrite)
	Set the value of an environment variable.
int	unsetenv (const char *name)
	Remove an environment variable.
int	uname (struct utsname *name)
	Get the name of the current system.
size_t	confstr (int name, char *buf, size_t len)
	Determine the value of a configurable system variable by name string.
int	getentropy (void *buffer, size_t length)
	Fill a buffer with cryptographically secure random bytes.
int	gethostname (char *name, size_t namelen)
	Get the name of the current host.
long	sysconf (int opt)
	Get a configurable system variable.

Detailed Description

POSIX Single Process option group.

Covers confstr(), sysconf(), gethostname(), getentropy(), and related single-process environment functions.

Function Documentation

confstr()

size_t confstr	(	int	name,
		char *	buf,
		size_t	len
	)

Determine the value of a configurable system variable by name string.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/confstr.html

getentropy()

int getentropy	(	void *	buffer,
		size_t	length
	)

Fill a buffer with cryptographically secure random bytes.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/getentropy.html

gethostname()

int gethostname	(	char *	name,
		size_t	namelen
	)

Get the name of the current host.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html

setenv()

int setenv	(	const char *	envname,
		const char *	envval,
		int	overwrite
	)

Set the value of an environment variable.

Parameters

envname	Name of the variable (must not contain '=').
envval	New value string.
overwrite	Non-zero to overwrite an existing value; 0 to preserve it.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/setenv.html

sysconf()

long sysconf

(

int

opt

)

Get a configurable system variable.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/sysconf.html

uname()

int uname

(

struct utsname *

name

)

Get the name of the current system.

Parameters

name	Output: system identification structure to fill in.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/uname.html

unsetenv()

int unsetenv

(

const char *

name

)

Remove an environment variable.

Parameters

name	Name of the variable to remove.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/unsetenv.html