We then need appropriate permission for the file itself, depending on how we're trying to open it: read-only, readwrite, and so on. This is why the execute permission bit for a directory is often called the search bit.įor example, to open the file "/usr/include/stdio.h", we need execute permission in the directory "/", execute permission in the directory "/usr", and execute permission in the directory "/usr/include". Whenever we want to open any type of file by name, we must have execute permission in each directory mentioned in the name, including the current directory, if it is implied. A type of file that points to another file. A socket can also be used for non-network communication between processes on a single host.ħ. A type of file used for network communication between processes. A type of file used for communication between processes. All devices on a system are either block special files or character special files.ĥ. A type of file providing unbuffered I/O access in variable-sized units to devices. A type of file providing buffered I/O access in fixed-size units to devices such as disk drives.Ĥ. Processes must use the functions described in this chapter to make changes to a directory.ģ. Any process that has read permission for a directory file can read the contents of the directory, but only the kernel can write directly to a directory file. A file that contains the names of other files and pointers to information on these files. All binary executable files conform to a format that allows the kernel to identify where to load a program's text and data.Ģ. To execute a program, the kernel must understand its format. One notable exception to this is with binary executable files. Any interpretation of the contents of a regular file is left to the application processing the file. There is no distinction to the UNIX kernel whether this data is text or binary. The most common type of file, which contains data of some form. Most files on a UNIX system are either regular files or directories, but there are additional types of files. We've talked about two different types of files so far: regular files and directories. Time_t st_ctime /* time of last file status change */īlksize_t st_blksize /* best I/O block size */īlkcnt_t st_blocks /* number of disk blocks allocated */ Time_t st_mtime /* time of last modification */ Time_t st_atime /* time of last access */ Off_t st_size /* size in bytes, for regular files */ Ino_t st_ino /* i-node number (serial number) */ĭev_t st_dev /* device number (file system) */ĭev_t st_rdev /* device number for special files */ Mode_t st_mode /* file type & mode (permissions) */
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