join is a command in

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 ...

and

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s that merges the lines of two sorted

text file A text file (sometimes spelled textfile; an old alternative name is flatfile) is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists stored as data within a computer file system. In operating ...

s based on the presence of a common

field Field may refer to: Expanses of open ground * Field (agriculture), an area of land used for agricultural purposes * Airfield, an aerodrome that lacks the infrastructure of an airport * Battlefield * Lawn, an area of mowed grass * Meadow, a grass ...

. It is similar to the join operator used in

relational database A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relatio ...

s but operating on text files.

Overview

The join command takes as input two text files and a number of options. If no

command-line argument A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

is given, this command looks for a pair of lines from the two files having the same first field (a sequence of characters that are different from space), and outputs a line composed of the first field followed by the rest of the two lines. The program arguments specify which

character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

to be used in place of space to separate the fields of the line, which field to use when looking for matching lines, and whether to output lines that do not match. The output can be stored to another file rather than printing using redirection. As an example, the two following files list the known fathers and the mothers of some people. Both files have been sorted on the join field — this is a requirement of the program. george jim kumar gunaware albert martha george sophie The join of these two files (with no argument) would produce: george jim sophie Indeed, only "george" is common as a first word of both files.

History

is intended to be a relation database operator. It is part of the

X/Open X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of info ...

Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX.1 and the Single Unix Specification. The version of join bundled in

GNU GNU () is an extensive collection of free software (383 packages as of January 2022), which can be used as an operating system or can be used in parts with other operating systems. The use of the completed GNU tools led to the family of operat ...

coreutils The GNU Core Utilities or coreutils is a package of GNU software containing implementations for many of the basic tools, such as cat, ls, and rm, which are used on Unix-like operating systems. In September 2002, the ''GNU coreutils'' were cr ...

was written by Mike Haertel. The command is available as a separate package for

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 ...

as part of the

UnxUtils UnxUtils is a collection of ports of common GNU Unix-like utilities to native Win32, with executables only depending on the Microsoft C- runtime msvcrt.dll. The collection was last updated externally on April 15, 2003, by Karl M. Syring. The mo ...

collection of

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

Win32 The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. The name Windows API collectively refers to several different platform implementations th ...

ports A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as H ...

of common GNU Unix-like utilities.

References

External links

* *
join command
Unix text processing utilities Unix SUS2008 utilities Plan 9 commands {{unix-stub

Overview

History

See also

References

External links