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Check all the true claims about the manual page of mq_receive provided below.

MQ_RECEIVE(3) Linux Programmer's Manual MQ_RECEIVE(3)

NAME

mq_receive, mq_timedreceive - receive a message from a message queue

SYNOPSIS

#include <mqueue.h>

ssize_t mq_receive(mqd_t mqdes, char *msg_ptr,

size_t msg_len, unsigned int *msg_prio);

#include <time.h>

#include <mqueue.h>

ssize_t mq_timedreceive(mqd_t mqdes, char *msg_ptr,

size_t msg_len, unsigned int *msg_prio,

const struct timespec *abs_timeout);

Link with -lrt.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

mq_timedreceive():

_POSIX_C_SOURCE >= 200112L

DESCRIPTION

mq_receive() removes the oldest message with the highest priority from the message queue referred to by the message queue de‐

scriptor mqdes, and places it in the buffer pointed to by msg_ptr. The msg_len argument specifies the size of the buffer pointed

to by msg_ptr; this must be greater than or equal to the mq_msgsize attribute of the queue (see mq_getattr(3)). If msg_prio is

not NULL, then the buffer to which it points is used to return the priority associated with the received message.

If the queue is empty, then, by default, mq_receive() blocks until a message becomes available, or the call is interrupted by a

signal handler. If the O_NONBLOCK flag is enabled for the message queue description, then the call instead fails immediately

with the error EAGAIN.

mq_timedreceive() behaves just like mq_receive(), except that if the queue is empty and the O_NONBLOCK flag is not enabled for

the message queue description, then abs_timeout points to a structure which specifies how long the call will block. This value

is an absolute timeout in seconds and nanoseconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC), specified in the following

structure:

struct timespec {

time_t tv_sec; /* seconds */

long tv_nsec; /* nanoseconds */

};

If no message is available, and the timeout has already expired by the time of the call, mq_timedreceive() returns immediately.

RETURN VALUE

On success, mq_receive() and mq_timedreceive() return the number of bytes in the received message; on error, -1 is returned, with

errno set to indicate the error.

O_NONBLOCK cannot be used with mq_timedreceive()

mq_receive() is a syscall

An extra library must be added to the compilation line to use mq_receive()

✅

mq_receive() always returns the number of bytes read

❌

No specific include is necessary for using mq_receive()

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Check all the true claims about the manual page of kill(1) provided below.

KILL(1) User Commands KILL(1)

NAME

kill - send a signal to a process

SYNOPSIS

kill [options] <pid> [...]

DESCRIPTION

The default signal for kill is TERM. Use -l or -L to list available signals. Particularly useful signals include HUP,

INT, KILL, STOP, CONT, and 0. Alternate signals may be specified in three ways: -9, -SIGKILL or -KILL. Negative PID val‐

ues may be used to choose whole process groups; see the PGID column in ps command output. A PID of -1 is special; it indi‐

cates all processes except the kill process itself and init.

OPTIONS

<pid> [...]

Send signal to every <pid> listed.

-<signal>

-s <signal>

--signal <signal>

Specify the signal to be sent. The signal can be specified by using name or number. The behavior of signals is ex‐

plained in signal(7) manual page.

-l, --list [signal]

List signal names. This option has optional argument, which will convert signal number to signal name, or other way

round.

-L, --table

List signal names in a nice table.

NOTES Your shell (command line interpreter) may have a built-in kill command. You may need to run the command described

here as /bin/kill to solve the conflict.

EXAMPLES

kill -9 -1

Kill all processes you can kill.

kill -l 11

Translate number 11 into a signal name.

kill -L

List the available signal choices in a nice table.

kill 123 543 2341 3453

Send the default signal, SIGTERM, to all those processes.

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