Sam is a multi-file

text editor A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be us ...

based on structural

regular expressions A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" o ...

. It was originally designed in the early 1980s at

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

Rob Pike Robert "Rob" Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell La ...

with the help of

Ken Thompson Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B programmi ...

and other Unix developers for the Blit windowing terminal running on

Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ...

; it was later ported to other systems. Sam follows a classical

modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...

aesthetic. It is internally simple, its power leveraged by the composability of a small command language and extensibility through shell integration.

Design and features

Sam is designed as two synchronous programs: a command interpreter and a mouse-oriented bitmap windowing interface. The interpreter's command set is modeled after the UNIX editor ed and may be used to operate the editor from a standard text terminal. By default, however, Sam presents its own

graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...

(GUI) window, ''samterm'', which additionally allows point-and-click operations through pop-up context menus. This two-process structure allowed sam to access files on networked host systems through remote execution of the file-access process while running the windowing interface locally, thereby bypassing latency over slow connections. Samterm presents windows to files being edited and to a persistent command window which accepts input as sam commands. Most common editing operations are quickly and naturally accomplished with the point-and-click interface, which also functions inside the command window. This latter fact allows commands to be edited (and resubmitted) just as any other text, a function inherited from the DMD 5620 terminal interface.

Command syntax

Sam's command syntax is formally similar to ed's or ex's, containing (structural-)

regular expression A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...

based conditional and loop functions and scope addressing, even sharing some of ed's syntax for such functions. But while ed's commands are line-oriented, sam's are selection-oriented. Selections are contiguous strings of text (which may span multiple lines), and are specified either with the mouse (by '' sweeping'' it over a region of text) or by a pattern match. Sam's commands take such selections as basic—more or less as other Unix tools treat lines; thus, multi-line and sub-line patterns are as naturally handled by Sam as whole-line patterns are by ed, vi,

AWK AWK (''awk'') is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool. Like sed and grep, it is a filter, and is a standard feature of most Unix-like operating systems. The AWK lang ...

Perl Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offici ...

, etc. This is implemented through a model called ''structural regular expressions'', which can recursively apply regular-expression matching to obtain other (sub)selections within a given selection. In this way, sam's command set can be applied to substrings that are identified by arbitrarily complex context. Sam extends its basic text-editing command set to handling of multiple files, providing similar pattern-based conditional and loop commands for filename specification. Any sequence of text-editing commands may be applied as a unit to each such specification.

Infinite undos

Sam was one of the first text editors to support "infinite" undo to revert any number of editing errors. This feature, combined with Sam's facility to easily edit its own commands and, fundamentally, its small, orthogonal command set (containing only 33 commands), represent the program's bias toward a low learning threshold over other more expressive "power editors."

Endorsers

Sam is the preferred text editor of several eminent programmers. It was the first full screen editor

liked. Sam is the text editor used by

Bjarne Stroustrup Bjarne Stroustrup (; ; born 30 December 1950) is a Danish computer scientist, most notable for the invention and development of the C++ programming language. As of July 2022, Stroustrup is a professor of Computer Science at Columbia University ...

Brian Kernighan Brian Wilson Kernighan (; born 1942) is a Canadian computer scientist. He worked at Bell Labs and contributed to the development of Unix alongside Unix creators Ken Thompson and Dennis Ritchie. Kernighan's name became widely known through co- ...

Douglas McIlroy Malcolm Douglas McIlroy (born 1932) is a mathematician, engineer, and programmer. As of 2019 he is an Adjunct Professor of Computer Science at Dartmouth College. McIlroy is best known for having originally proposed Unix pipelines and developed se ...

and

Tom Duff Tom or TOM may refer to: * Tom (given name), a diminutive of Thomas or Tomás or an independent Aramaic given name (and a list of people with the name) Characters * Tom Anderson, a character in '' Beavis and Butt-Head'' * Tom Beck, a character ...

. Others, like Dennis Ritchie,

and Russ Cox, have transitioned to acme, an editor with the same command language as sam, but with an assortment of additional features, including

mouse chording Mouse chording is the capability of performing actions when multiple mouse buttons are held down, much like a chorded keyboard and similar to mouse gestures. One common application of mouse chording, called ''rocker navigation'', is found in Ope ...

and automatic tiling of opened files. The latest version of sam was written as part of the Plan 9 operating system, but there are

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...

and

X Window System The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wit ...

ports available.

Notes

References

* * *

External links

ssam(1): stream interface to samSam Resourcessam(1): screen editor with structural regular expressionsA Win32 version of samA new Win32 version of sam and other plan9 utilities based on plan9portA new Unix version of sam
as part of

Plan 9 from User Space Plan 9 from User Space (also plan9port or p9p) is a port of many Plan 9 from Bell Labs libraries and applications to Unix-like operating systems. Currently it has been tested on a variety of operating systems including: Linux, macOS, FreeBSD, Net ...

Another version of sam for Unix
without any

dependencies and with scalable font support
A sam quick reference card
{{DEFAULTSORT:Sam (Text Editor) Free text editors Plan 9 from Bell Labs Inferno (operating system) Unix text editors MacOS text editors Windows text editors