Simple example of threads running simultaneously

pthreads-example.c

#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>

#define EXIT_TIMEOUT 1
#define THREAD_COUNT 3

pthread_t tid[THREAD_COUNT];

void* worker(void *arg)
{
	pthread_t id = pthread_self();

	int ix = -1;
	for (int i = 0; i < THREAD_COUNT; i++)
		if (pthread_equal(id, tid[i]))
			ix = i + 1;

	while (1)
		printf("[%d]: Thread working ...\n", ix);

	return NULL;
}

int main(void)
{
	int err;

	for (int i = 0; i < THREAD_COUNT; i++)
	{
		err = pthread_create(&(tid[i]), NULL, &worker, NULL);
		if (err != 0)
			printf("Error creation failed with error \"%s\"", strerror(err));
		else
			printf("[%d]: Thread created successfully\n", i + 1);
	}

	sleep(EXIT_TIMEOUT);

	printf("\n");

	return 0;
}

run.sh

#!/bin/bash

# support macOS by default
function is_linux
{
	if [[ "$(uname)" == "Linux" ]]; then
		echo 1
		return
	fi

	echo 0
}

OUT="output.log"
APP="pthreads_example.out"
SRC=$(ls *.c)
CFLAGS=""
PS="ps -M "

if [[ "$(is_linux)" == "1" ]]; then
	CFLAGS="-pthread"
	PS="ps -Lf -p "
fi

cc ${CFLAGS} -o ${APP} ${SRC}
./${APP} > ${OUT} &

PID=$(ps x | grep -v grep | grep ${APP} | awk '{$1=$1;print}' | cut -d ' ' -f 1)
${PS} ${PID}

sleep 1
head -n 20 ${OUT}
tail -n 20 ${OUT}

rm ${APP} ${OUT}