fcntl

embedded Linux system Programming (ii)--File Descriptor control function fcntl Because the fcntl function is too flexible and complex, the fcntl function is listed separately from the file IO , which is easy to read in detail. The function

For the Open function O_cloexec mode, the FCNTL function fd_cloexec option is summarized as follows: Calling the Open function O_cloexec mode opens a file descriptor that is closed in a new program that executes the exec call, and is an

Use the following method to set the socket to non-blocking mode:Int flags = fcntl (socket, F_GETFL, 0 );Fcntl (socket, F_SETFL, flags | O_NONBLOCK );Use the following method to set the socket to non-blocking mode:Int flags = fcntl (socket, F_GETFL, 0

Fcntl. h and unistd. h2008-08-22 22: 15fcntl. h define a lot of macro and open, fcntl function prototypeUnistd. h defines more function prototypes Close (close the file)Header file # include Defines the int close (int fd) function );Function

Transfer from http://www.cnblogs.com/xuyh/p/3273082.htmlSet file flags with command F_GETFL and F_SETFL, such as blocking and non-blockingF_SETFL set to the ARG descriptor status flag, several flags that can be changed are: O_append,

How to operate a file that has been shared, that is, how to ensure the correctness of file data when multiple processes operate on the same file at the same time. Linux usually uses File Locking to avoid competition for shared resources. File locks

There are two types of fcntl File locks: Create locksAnd Mandatory lock The locks are defined as follows: every process that uses a lock file must check whether a lock exists. Of course, you must respect the existing locks. In general, the kernel

The Fcntl () function can change the nature of an open file#include #include int fcntl (int fd, int cmd);int fcntl (int fd, int cmd, long arg);int fcntl (int fd, int cmd, struct flock * lock);Fcntl () is used to manipulate some of the

FCNTL system CallExample 1: Status flags for a fileMyfcntl_access.c#include #include#include#include#include#include#include#defineERROR (flag)if(flag) {printf ("%d:", __line__); Fflush (stdout); Perror ("Error");

Use fcntl () to set the blocking nature of the blocking function. The fcntl Function #include #include #include #include #include #include #include #define ERR_EXIT(m) \ do { \ perror(m);\ exit(EXIT_FAILURE);\ }while(0)void

1. DUP functionThe 1.1 DUP function is used to copy a file descriptor , and the copied file descriptor can be used normally (see Example 1). The DUP function returns one of the smallest available file descriptors in the current File descriptor table

Records lock record Locking Function: When a process is reading or modifying a part of a file, it can prevent other processes from modifying the same file area. BYTE range lock Byte-range locking Second, history Flock function, you can lock the

Fcntl system call]Function Description: describes the features of a file based on its description.Usage:Int fcntl (int fd, int cmd );Int fcntl (int fd, int cmd, long Arg );Int fcntl (int fd, int cmd, struct flock * Lock );Parameters:FD: file

int fcntl (int fd,int cmd,...)The function Fcntl provides a very rich feature. The main dependencies are the various parameters of CMD: Copy an existing file descriptor F_dupfd,f_dupfd_cloexec Gets the flag for the set file descriptor F_

The fcntl function can change the nature of opened files. #include fcntl( filedes, cmd, ... - In each instance in this section, the third parameter is always an integer, which corresponds to the annotation section in the function prototype shown

In Linux, the functions used to implement File locks include lock and fcntl, where lock is used to apply a commit lock to the file, while fcntl can not only apply a mandatory lock, but also apply a commit lock. At the same time, fcntl can lock a

/DUP function: copy an existing handle to generate a new handle that is exactly the same as the "source handle feature" (that is, generate a new handle number, and associated with the same device)// Functions of the dup2 function: copy an existing

Fcntl (file lock)Header file # include # Include Function Definition int fcntl (int fd, int cmd, struct flock * Lock );Function Description FD: file descriptorThe configured file descriptor. The cmd parameter indicates the command to

getsockopt () Briefly:Gets a set of interface options.#include int PASCAL FAR getsockopt (SOCKET s, int level, int optname,Char far* optval, int far* optlen);S: A descriptive word that identifies the socket interface.Level: The

Introduction:For an ordinary file, we can think of the operation of it, read the contents of the file, write the data to the file, these are mentioned in the previous read, write function. In addition, you can also get other properties of the file,