Shulou(Shulou.com)06/03 Report--

Everything in Linux is a file!

This piece of content is mainly a variety of operations on Linux files: open, close, new, read, write, etc., C functions (not Shell commands!) As follows:

int open(const char *path,int oflags,mode_t mode)

[path: path/oflags: open mode (see Note 2)/mode: permission/return: handle, error: -1]

Note 1: If the file does not exist, create it.

Note 2: oflags are:

O_RDONLY: file read-only;(similar to "open as read-only" in excel to protect the file from being altered)

O_WRONLY: file write only;

O_RDWR: file readable and writable;

O_NOCTTY: If the path points to a terminal, the device is not used as the control terminal for this process (it can still be used if the path is a terminal console);

O_NDELAY: Non-blocking mode operation file

Note 3: A handle is actually a pointer to a file structure, like holding up a card in a crowd to say "I'm here, something's coming for me"

int close(int fd)

fd: Handle of an open file

int creat(const char *pathname,mode_t mode)

[path: path/mode: permission]

ssize_t read(int fd,void *buf,size_t len)

[fd: Handle of opened file/buf: Storage location of read data/len: Length of read data (bytes)/return: Actual number of bytes of read data, Error: -1]

ssize_t write(int fd,void *buf,size_t count)

[fd: Handle of opened file/buf: Data to be written/count: Length of data to be written (bytes)/return: Actual number of bytes of data written, Error: -1]

4 header files for file operations:

#include

#include

#include

#include

Where are the above header files at ×××? Type "man 2 open" under shell.

P.S. In order to better understand this chapter, it is recommended to review the relevant contents of Tan Haoqiang's C Language Programming (Fourth Edition), which has some conceptual things, fopen (), fclose (), etc.

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