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A03 - Unix File Systems
Terms in this set (57)
In Unix, define a FILE
A file is any source from which data can be read or any destination to which data can be written
In Unix, how many characters can a filename contain?
Up to 255 characters depending on the specific implementation
A filename can be any sequence of ASCII characters except ...?
A filename that starts with a period is a ...?
Define SIMPLE / REGULAR FILES
Files that contain normal data; e.g., text files, executable files or programs, input for or output from programs
Files that are lists of simple files and/or other directories (sub-directories); a file consisting of an array of directory entries
Define INODE NUMBER
A 4-byte long index value for the array of index nodes on the disk; containing file attributes
Define LINK FILE
A file that makes another file or directory visible in multiple parts of the system's file tree
Define SPECIAL FILE
Mechanisms used for the input and output; divided into (1) Character-oriented devices (e.g., keyboards, etc.); (2) Block-oriented devices (e.g., disk, printer, etc.)
Inter-Process Communication (IPC) are UNIX mechanisms that enable processes to communicate with each other; the most often used IPC primitives are: (1) Pipes; (2) Named pipes (FIFO); (3) Sockets
An area in the kernel memory (kernel buffer) that allows two processes to communicate with each other, in case that processes are running on the same computer system and are related to each other
(Domain) socket is a special file type, similar to TCP/IP sockets, providing inter-process networking protected by the file system's access control
Define NAMED PIPE
(FIFO) is a file that allows two processes to communicate with each other if they are running on the same computer. Processes do not have to be related to each other
The UNIX system has a [...], file structure
Define ROOT DIRECTORY
The highest level in the UNIX hierarchy structure; the root of the entire file structure
Define WORKING DIRECTORY
The current / working directory is the one we are in at any point in a session, represented by the period "." notation
Define PARENT DIRECTORY
The immediate directory above the working directory, represented by double period ".." notation
Define ABSOLUTE PATHNAME
It starts with the root directory and contains all the filenames that trace a path to a given file (e.g., /home/faculty/file.txt)
When the user logs on, the system puts them into their [...], which is usually subdirectory of the system's [...] directory; represented by the [...] symbol
(1) Home directory;
(3) Tilde "~'
Define RELATIVE PATHNAME
The path that starts from the presently working directory (e.g., /unix/asg1.txt)
Define SIMPLE PATHNAME
The path that is the last element of the pathname and is a form of relative pathname
What are the 18 subdirectories of the ROOT DIRECTORY?
What are the contents of the /bin directory?
Common programs, shared by the system, the system administrator and the users
What are the contents of the /boot directory?
The startup files and the kernel, vmlinuz. In recent distributions also grub (GRand Unified Boot loader data)
What are the contents of the /dev directory?
Contains references to all the CPU peripheral hardware, which are represented as files with special properties
What are the contents of the /etc directory?
Most important system configuration files
What are the contents of the /home directory?
Home directories of the common users
What are the contents of the /initrd directory?
(on some distributions) information for booting
What are the contents of the /lib directory?
Library files, including files for all kinds of programs needed by the system and the users
What are the contents of the /lost+found directory?
Every partition has a lost+found in its upper directory. Files that were saved during failures are here
What are the contents of the /misc directory?
For miscellaneous purposes
What are the contents of the /mnt directory?
Standard mount point for external file systems (e.g., CD-ROM, DVD drive, or a digital camera)
What are the contents of the /net directory?
Standard mount point for entire remote file systems
What are the contents of the /opt directory?
Typically contains extra and third party software
What are the contents of the /proc directory?
A virtual file system containing information about system resources
What are the contents of the /root directory?
The administrative user's home directory. Mind the difference between /, the root directory and /root, the home directory of the root user
What are the contents of the /sbin directory?
Programs for use by the system and the system administrator
What are the contents of the /tmp directory?
Temporary space for use by the system
What are the contents of the /usr directory?
Programs, libraries, documentation, etc., for all user-related programs
What are the contents of the /var directory?
Storage for all variable files and temporary files created by user, such as log files, the mail queue, the print spooler area, space fir temporary storage of files downloaded from the Internet, or to keep an image of a CD before burning it
All shell and configuration files have filenames that begin with the [...] symbol, but why?
(2) They're all hidden files
Define the "pwd" command
(Print Working Directory) displays the pathname of the working directory
Define the "ls" command
(List Directory) lists the files and directories of the directory the user is in, or which the user specifies
Define the "mkdir" command
(Make Directory) creates directories
Define the "cd" command
(Change Directory) makes another directory the working directory
Define the "rmdir" command
(Remove Directory) deletes empty directories
Define the `touch` command
Creates an empty file
Define the `cat` command
Define the `more`command
Views files one page at a time
Define the `less` command
Views files in the file list one page at a time
Define the `head` command
Displays the beginning portion of files
Define the `tail` command
Displays the last portion of files
Define the `wc` command
Displays size of the files in the file list, as number of lines, words, and characters
Define the `uniq` command
Removes repetitious lines from the sorted 'input-file' and send unique lines to 'output-file'
Define the `ln` command
Creates a link (pointer) destination to source files and/or directories
Define the `rm` command
Removes the file(s)
Define the `find` command
Searches file names, using file size, date of last change, and other file properties as criteria
THIS SET IS OFTEN IN FOLDERS WITH...
02 - Structure of Unix
05 - File Structure and Processing
01 - Intro to UNIX OS
A01 - Getting Started
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