Multi-process programming, Wang Ming Learning Learn

Multi-process programming

First, function learning

1.1 Creating a Process fork

1.1.1 Function prototype

pid_t fork (void);

1.1.2 Function function

Create a child process

1.1.3 Owning header file

<unistd.h>

1.1.4 return value

Success: The parent process returned a successfully created child process PID subprocess returned 0

Failed: Parent Process returned

1.1.5 parameter Description

No

1.2 Creating a process vfork

1.2.1 Function prototype

pid_t vfork ();

1.2.2 Function function

Create a child process and block the parent process

1.2.3 Owning header file

<sys/types.h> <unistd.h>

1.2.4 return value

Success: The parent process returned a successfully created child process PID subprocess returned 0

Failed: Parent process returned-1

1.2.5 Parameter Description

No

Fork and vfork Contrast:

Both fork and vfork can be used to create child processes, but there are also the following differences:

1. Fork: The child process has separate data segments, stacks. Vfork: The child process shares the data segment with the parent process, the stack.

2. Fork: The order of execution of the parent and child processes is indeterminate vfork: Child processes run first, run after the parent process

1.3 Process waiting wait

1.3.1 Function prototype

pid_t Wait (int* status);

1.3.2 Function function

Suspends the process that invokes it until its child process ends

1.3.3 Owning header file

<sys/types.h> <sys/wait.h>

1.3.4 return value

Success: Returns the end of the child process ID

Failed:-1

1.3.5 parameter Description

Status: Record child process exit status

1.4 Execution Program function name execl

1.4.1 Function prototype

int execl (const char* pathname,const char*arg,...)

1.4.2 function function

Run an executable file

1.4.3 Owning header file

<unsitd.h>

1.4.4 return value

Success: Do not return

Failed: Return

1.4.5 parameter Description

Pathname: The path to the executable file to run

ARG: The parameters required to run the executable file

1.5 terminating the process Exit equals _exit

1.5.1 function prototype

void _exit (int status)

1.5.2 function function

Terminates the process being called

1.5.3 Owning header file

<unistd.h>

1.5.4 return value

No

1.5.5 parameter Description

Status is used as a city exit status returned to the parent process

Parent Process exit: can be return 0 and exit

Child process exit: only exit

Multi-process programming, Wang Ming Learning Learn