JOIN (UNIX)
LAMBERT M. SURHONE, MARIAM T. TENNOE, SUSAN F. HENSSONOW
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Join is a command in Unix-like operating systems that merges the lines of two sorted text files based on the presence of a common field.
It is similar to the join operator used in relational databases but operating on text files.
The join command takes as input two text files and a number of options.
If no command-line argument 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 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.
