In this post, we create a simple thread using pthread library API “pthread_create” and wait for this thread to execute in main using pthread_join. $ vim simple-linux-thread-using-pthread.c #include <stdio.h> #include <stdlib.h> #include <pthread.h> void *functioncalledbythread(void *arg) { int count = 0, i; int *passed_value = (int*)arg; printf("Value passed to thread from main : %d \n", *passed_value); for(i=0; i < 10; i++) { count++; sleep(1); } return NULL; } int main(int argc, char **argv) { int retval; pthread_t threadId; int pass_this_val = 5; printf("Creating simple thread\n"); if((retval = pthread_create(&threadId, NULL, &functioncalledbythread, (void *)&pass_this_val))) { printf("Thread creation failed: %d\n", retval); } printf("Waiting in main for thread to finish\n"); /* Wait till threads are complete before main continues.*/ pthread_join(threadId, NULL); printf("Thread execution finished, exiting from main program\n"); exit(0); } The above program is self explanatory which creates a simple thread using pthread library API “pthread_create” which returns unique Thread ID in first argument threadId, and we pass two other arguments, a function pointer (functioncalledbythread) which points to the function called by the thread when it executes and void pointer which we can use to pass the values to the called function from main process to thread. (pass_this_val) At the end we used pthread_join to make sure we wait in main application to let the thread complete its work before the main application terminates.

Command line execution

Terminalbash
sed to thread from main : %d \n", *passed_value);       for(i=0; i < 10; i++) {         count++;         sleep(1);     }     return NULL;  }   int main(int argc, char **argv) {     int retval;     pthread_t threadId;     int pass_this_val = 5;       printf("Creating simple thread\n");     if((retval = pthread_create(&threadId, NULL, &functioncalledbythread, (void *)&pass_this_val))) {         printf("Thread creation failed: %d\n", retval);     }       printf("Waiting in main for thread to finish\n");     /* Wait till threads are complete before main continues.*/     pthread_join(threadId, NULL);       printf("Thread execution finished, exiting from main program\n");     exit(0); } The above program is self explanatory which creates a simple thread using pthread library API “pthread_create” which returns unique Thread ID in first argument threadId, and we pass two other arguments, a function pointer (functioncalledbythread) which points to the function called by the thread when it executes and void pointer which we can use to pass the values to the called function from main process to thread. (pass_this_val) At the end we used pthread_join to make sure we wait in main application to let the thread complete its work before the main application terminates.  $ gcc -o simple-linux-thread-using-pthread simple-linux-thread-using-pthread.c -lpthread  $ ./simple-linux-thread-using-pthread Creating simple thread Waiting in main for thread to finish Value passed to thread from main : 5  Thread execution finished, exiting from main program

Implementation details

$ gcc -o simple-linux-thread-using-pthread simple-linux-thread-using-pthread.c -lpthread $ ./simple-linux-thread-using-pthread Creating simple thread Waiting in main for thread to finish Value passed to thread from main : 5 Thread execution finished, exiting from main program

Gotchas and common issues

  • Permission checks - verify user access rights and sudo privileges before executing system-level operations.

  • Environment configuration - double-check path variables and dependency versions to prevent runtime failures.

  • Backup safeguards - maintain configuration backups before applying system or database modifications.

Following these steps ensures clean configuration and reliable execution for creating a simple thread in linux using pthread library api’s.