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A page break is a marker in an electronic document that tells the document interpreter that the content which follows is part of a new page. A page break causes a form feed to be sent to the printer during spooling of the document to the printer. Thus it is one of the elements that contributes to pagination.
Form feed is a page-breaking ASCII control character. It directs the printer to eject the current page and to continue printing at the top of another. Often, it will also cause a carriage return. The form feed character code is defined as 12 (0xC in hexadecimal), and may be represented as Ctrl+L or ^L. In a related use, Ctrl+L can be used to clear the screen in Unix shells such as bash, or redraw screen in TUI programs like vi/emacs. In the C programming language (and other languages derived from C), the form feed character is represented as '\f'. Unicode also provides the character U+21A1↡DOWNWARDS TWO HEADED ARROW as a printable symbol for a form feed (not as the form feed itself). [1] The form feed character is considered whitespace by the C character classification function isspace().
Form feed is seldom used when programming with modern printers in modern operating environments like Windows, Unix, Linux or macOS. Instead, form feeds are generated by having the printing program call a form feed API function. For example, when printing using the .NET Framework, the PrintPageEventArgs.HasMorePages property is used to indicate a form feed is desired.
The form feed character is sometimes used in plain text files of source code as a delimiter for a page break, or as marker for sections of code. Some editors, in particular emacs and vi, have built-in commands to page up/down on the form feed character. This convention is predominantly used in Lisp code, and is also seen in C and Python source code. GNU Coding Standards require such form feeds in C. [2]
In Usenet, the form feed character is used by several newsreaders as a "spoiler character", causing them to automatically hide the following text until prompted, as a way to prevent spoilers from being inadvertently revealed. [3] The precise behavior depends on the client displaying the article: for example, Gnus displays "Next page..." in boldface, and switches to a second screen to display text after the form feed; slrn displays all non-space characters following the form feed as asterisks; Dialog turns the font and background color red between form feeds; and XRN simply inserts blank lines to fill up the remainder of the article display area so the user must scroll down to reveal the spoiler. This use of the form feed character is not supported by all newsreaders, and is not standardized, although it has appeared in a draft of a Usenet Best Practices document by the IETF's USEFOR working group, as a feature that user agents should (but are not required to) support. [4]
ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of technical limitations of computer systems at the time it was invented, ASCII has just 128 code points, of which only 95 are printable characters, which severely limited its scope. Modern computer systems have evolved to use Unicode, which has millions of code points, but the first 128 of these are the same as the ASCII set.
In computing and telecommunication, a control character or non-printing character (NPC) is a code point in a character set that does not represent a written character or symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly graphic characters, also known as printing characters, except perhaps for "space" characters. In the ASCII standard there are 33 control characters, such as code 7, BEL, which rings a terminal bell.
The editor war is the rivalry between users of the Emacs and vi text editors. The rivalry has become an enduring part of hacker culture and the free software community.
vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.
WordStar is a word processor application for microcomputers. It was published by MicroPro International and originally written for the CP/M-80 operating system, with later editions added for MS-DOS and other 16-bit PC OSes. Rob Barnaby was the sole author of the early versions of the program.
In computing, a Control keyCtrl is a modifier key which, when pressed in conjunction with another key, performs a special operation. Similarly to the Shift key, the Control key rarely performs any function when pressed by itself. The Control key is located on or near the bottom left side of most keyboards, with many featuring an additional one at the bottom right.
Gnus, or Gnus Network User Services, is a message reader which is part of GNU Emacs. It supports reading and composing both e-mail and news and can also act as an RSS reader, web processor, and directory browser for both local and remote filesystems.
A carriage return, sometimes known as a cartridge return and often shortened to CR, <CR> or return, is a control character or mechanism used to reset a device's position to the beginning of a line of text. It is closely associated with the line feed and newline concepts, although it can be considered separately in its own right.
A newline is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a sequence of characters, is used to signify the end of a line of text and the start of a new one.
Pretty-printing is the application of any of various stylistic formatting conventions to text files, such as source code, markup, and similar kinds of content. These formatting conventions may entail adhering to an indentation style, using different color and typeface to highlight syntactic elements of source code, or adjusting size, to make the content easier for people to read, and understand. Pretty-printers for source code are sometimes called code formatters or beautifiers.
In computing, text-based user interfaces (TUI), is a retronym describing a type of user interface (UI) common as an early form of human–computer interaction, before the advent of bitmapped displays and modern conventional graphical user interfaces (GUIs). Like modern GUIs, they can use the entire screen area and may accept mouse and other inputs. They may also use color and often structure the display using box-drawing characters such as ┌ and ╣. The modern context of use is usually a terminal emulator.
A bell character is a device control code originally sent to ring a small electromechanical bell on tickers and other teleprinters and teletypewriters to alert operators at the other end of the line, often of an incoming message. Though tickers punched the bell codes into their tapes, printers generally do not print a character when the bell code is received. Bell codes are usually represented by the label "BEL". They have been used since 1870.
This article provides basic comparisons for notable text editors. More feature details for text editors are available from the Category of text editor features and from the individual products' articles. This article may not be up-to-date or necessarily all-inclusive.
GNU Readline is a software library that provides in-line editing and history capabilities for interactive programs with a command-line interface, such as Bash. It is currently maintained by Chet Ramey as part of the GNU Project.
Unicode input is the insertion of a specific Unicode character on a computer by a user; it is a common way to input characters not directly supported by a physical keyboard. Unicode characters can be produced either by selecting them from a display or by typing a certain sequence of keys on a physical keyboard. In addition, a character produced by one of these methods in one web page or document can be copied into another. In contrast to ASCII's 96 element character set, Unicode encodes hundreds of thousands of graphemes (characters) from almost all of the world's written languages and many other signs and symbols besides.
od is a command on various operating systems for displaying ("dumping") data in various human-readable output formats. The name is an acronym for "octal dump" since it defaults to printing in the octal data format.
GNU Emacs is a free software text editor. It was created by GNU Project founder Richard Stallman, based on the Emacs editor developed for Unix operating systems. GNU Emacs has been a central component of the GNU project and a flagship project of the free software movement. Its tag line is "the extensible self-documenting text editor."
Emacs, originally named EMACS, is a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, self-documenting, real-time display editor". Development of the first Emacs began in the mid-1970s, and work on GNU Emacs, directly descended from the original, is ongoing; its latest version is 29.2, released January 2024.
cat is a standard Unix utility that reads files sequentially, writing them to standard output. The name is derived from its function to (con)catenate files . It has been ported to a number of operating systems.