Linux application Development-process programming

You must understand the basic concepts before learning:

process, thread, process 3 states, process scheduling and 4 algorithms, process synchronization, deadlock, can't remember to find Niang.

Get ID

#include <sys/types.h>

#include <unistd.h>

Get this process ID:

pid_t getpid (void)

Get Parent Process ID:

pid_t getppid (void)

Example:

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

int main (void)

{

printf ("pid=%d\n", Getpid ());

printf ("pid=%d\n", Getppid ());

return 0;

}

Process creation:

#include <unistd.h>

pid_t fork (void)

Create a child process, be called once, return two times, possibly 3 kinds of values;

1. In the parent process, the child process PID is returned;

2. In the sub-process, return 0;

3. Error returns a negative value;

The data space for the child process, and the stack space is copied from the parent process, not shared.

-vfork

pid_t vfork (void)

Difference: The Vfork child process shares the data segment with the parent process.

The Vfork child process executes first, after the parent process.

The order of Fork is uncertain;

exec function Family:

The program being executed replaces the program that called it:

Difference:

Fork creates a new process that produces a new PID;

EXEC starts a new program, replaces the original process, and the PID does not change.

#include <unistd.h>

int execl (const char*path,const CHAR*ARG1,...);

Path: The name of the program being executed

ARGN: command-line arguments, with parameter names, ending with a null pointer (NULL)

Example:

#include <unistd.h>

Main ()

{

Execl ("/bin/ls", "ls", "-al", "/etc/passwd", (char*) 0);

}

#include <unistd.h>

int EXECP (const char*path,const CHAR*ARG1,...);

Path: The name of the program being executed (without the path, as found in the PATH environment variable).

Exmple

EXECP ("ls", "ls", "-al", "/etc/passwd", (char*) 0);

#include <unistd.h>

int Execv (const char*path, char*const argv[]);

Example

#include <unistd.h>

Main
{

char *argvl[]={"ls", "-al", "/etc/passwd", (char*) 0};

EXECV ("/bin/ls", argv);

}

#include <stdlib.h>

int system (const char*sring);

Call fork to produce a child process that calls/bin/sh-c string to execute the command represented by the argument string.

E:

System ("ls-al/etc/passwd");

Process waits:

#include <sys/types.h>

#include <sys/wait.h>

pid_t Wait (int*status)

Block the process until a process exits.

　　

Linux application Development-process programming