Owlcom software
basadO wlCom  Software
Let's Owl manage your files
Welcome Screenshots Buy now Download Write to Owl Subscribe to news FAQ Links

Organization of the file system

Some operations to the files. In the previous chapter lists the basic operations on files. This section will describe the modus operandi of some system calls to work with the file system, following mainly in the light together, imposed in this chapter concepts. Systemic challenges of working with the symbolic name of the file. System Challenges linking pathname to the file descriptor It features and open it. For example, the Unix OS fd = creat (pathname, modes); fd = open (pathname, flags, modes); Other operations to the files, such as read, write, read-write head positioning, reproduction descriptor file, the installation of I / O parameters, the definition of the status of the file and the closure of the file, use the value received descriptor file. Consider the work of open system call. Logical file subsystem scans the file system in search of the file on his behalf. It checks the right to open a file and provides open file table entry files. Writing tables file contains a pointer to knot the index file open. The kernel provides personal record in the table (closed) in the address space of the process, highlighted the process (see table, this table is called a custom file descriptors), and stores a pointer to this entry. The index stands file descriptor returned by the user. Writing in the table of user files indicates record in the global table files. The first three user descriptor (0, 1 and 2) called descriptor files: standard input, standard output, and standard error file. The processes in the system used by agreement UNIX file descriptor entry while reading standard input, standard output file descriptor while writing and the output file descriptor standard errors for writing error messages. Tying File System function link connects file with a new name in the file system directory structure, creating a new index for the existing entry in the directory. Syntax function call link: link (source file name, target file name); where the source file name, the name of an existing file, and target file name is a new (additional) name given to a file after the function link. First OS determines the location of the source file and the index increases inflated links in the index node. Then, the kernel looks for a file with a new name, if it exists, the function failed link is completed and restores the old kernel
Next part
Welcome    Screenshots    Download    Buy now Write to Owl    Subscribe to Owl news   FAQ   Links  
Copyright 2004-2008 OwlCom Software .

OISV - Organization of Independent Software Vendors - Contributing Member Software Submit .NET - FREE and PREMIUM search engines submission and software submission and software promotion service. Owl Commander
Locations of visitors to this page

Valid HTML 4.01 Transitional