Understand the benefits of Unix I / O's
Learn Unix I / O will help us understand other system concept
I / O is an integral part of the operating system, therefore, we often encounter a circular dependency between the I / O and other system concepts. For example, I / O plays a key role in the creation and implementation process in. In turn, the process of creation and plays a key role in sharing files among different processes. Therefore, to truly understand the I / O, we must understand the process, and vice versa. In the discussion of the memory hierarchy, linking and loading, as well as the process virtual memory, we have contacted some aspects of I / O, on this basis, we can close the whole cycle, to better study the I / O.
Application opens a file process
An application to open the corresponding file by requiring the kernel to declare it a I want to visit / O devices. The kernel returns a small non-negative integer called a descriptor, which identifies the document in all operations subsequent to this file. All information recorded on this kernel files open. Just remember this application descriptor.
This identifies the file descriptor is the file descriptor (File Description, referred fd)
EOF
end of file
Difference between ordinary files and binary files
Ordinary file contains any data. Applications often have to distinguish between text and binary files, text files are ASCII files contain only plain or Unicode characters; binaries are all the other files. For the kernel, text and binary files is no different.
The socket concept, need to be clear in my heart
Sockets are used for communication across a network with another process files
In Linux, the English period (.), The current directory
Know some of this is good for ordinary operations performed on Linux