How to get the process ID in C language? (code example)

We can use the getppid() and getpid() functions to obtain the process ID. They are both built-in functions defined in the unistd.h library and can return the process ID. The following article will give you a brief introduction to the getppid() and getpid() functions, and learn how to obtain the process ID using C language in the Linux system. I hope it will be helpful to you.

getpid() function

When any process is created, it has a unique id, called is the process ID. The getpid() function returns the process ID of the calling process. [Video tutorial recommendation:C Language Tutorial]

Basic syntax:

pid_t getpid(void);

Return type: The getpid() function returns the process ID of the current process; it never throws no errors occur and therefore always succeeds.

getppid() function

getppid() function: Returns the process ID of the parent process of the calling process.

Description: If the calling process was created by the fork() function, and the parent process still exists when the getppid() function is called, this function returns the process ID of the parent process. Otherwise, this function returns the value 1, which is the process ID of the init process.

Basic syntax:

pid_t getppid(void);

Return type: The getppid() function returns the process ID of the parent process of the current process; it never throws any error, so it always succeeds.

Note:pid_t is the type of process ID, which is an unsigned integer data type.

Code example (C language):

Let’s take a look at how to obtain the calling process ID and parent process ID using C language in the Linux system .

#include  #include  #include  int main(void) { //存储调用函数进程ID的变量 pid_t process_id; //存储父函数进程ID的变量 pid_t p_process_id; //getpid() - 将返回调用函数的进程ID process_id = getpid(); //getppid() - 将返回父函数的进程ID p_process_id = getppid(); //输出进程ID printf("调用函数的进程ID：%d\n",process_id); printf("父函数的进程ID：%d\n",p_process_id); return 0; }

Output:

调用函数的进程ID：31120 父函数的进程ID：31119

Description: Header file

● stdio.h: used for printf() function

● sys/types.h: For the pid_t type, the data type of the variable used to store the process ID.

●unistd.h: used for getpid() and getppid() functions

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