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JOIN(1)			FreeBSD	General	Commands Manual		       JOIN(1)

     join -- relational	database operator

     join [-a file_number | -v file_number] [-e	string]	[-o list] [-t char]
	  [-1 field] [-2 field]	file1 file2

     The join utility performs an "equality join" on the specified files and
     writes the	result to the standard output.	The "join field" is the	field
     in	each file by which the files are compared.  The	first field in each
     line is used by default.  There is	one line in the	output for each	pair
     of	lines in file1 and file2 which have identical join fields.  Each out-
     put line consists of the join field, the remaining	fields from file1 and
     then the remaining	fields from file2.

     The default field separators are tab and space characters.	 In this case,
     multiple tabs and spaces count as a single	field separator, and leading
     tabs and spaces are ignored.  The default output field separator is a
     single space character.

     Many of the options use file and field numbers.  Both file	numbers	and
     field numbers are 1 based,	i.e., the first	file on	the command line is
     file number 1 and the first field is field	number 1.  The following op-
     tions are available:

     -a	file_number
	     In	addition to the	default	output,	produce	a line for each	un-
	     pairable line in file file_number.

     -e	string
	     Replace empty output fields with string.

     -o	list
	     The -o option specifies the fields	that will be output from each
	     file for each line	with matching join fields.  Each element of
	     list has either the form file_number.field, where file_number is
	     a file number and field is	a field	number,	or the form `0'
	     (zero), representing the join field.  The elements	of list	must
	     be	either comma (`,') or whitespace separated.  (The latter re-
	     quires quoting to protect it from the shell, or, a	simpler	ap-
	     proach is to use multiple -o options.)

     -t	char
	     Use character char	as a field delimiter for both input and	out-
	     put.  Every occurrence of char in a line is significant.

     -v	file_number
	     Do	not display the	default	output,	but display a line for each
	     unpairable	line in	file file_number.  The options -v 1 and	-v 2
	     may be specified at the same time.

     -1	field
	     Join on the field'th field	of file1.

     -2	field
	     Join on the field'th field	of file2.

     When the default field delimiter characters are used, the files to	be
     joined should be ordered in the collating sequence	of sort(1), using the
     -b	option,	on the fields on which they are	to be joined, otherwise	join
     may not report all	field matches.	When the field delimiter characters
     are specified by the -t option, the collating sequence should be the same
     as	sort(1)	without	the -b option.

     If	one of the arguments file1 or file2 is `-', the	standard input is

     The join utility exits 0 on success, and >0 if an error occurs.

     Assuming a	file named nobel_laureates.txt with information	about some of
     the first Nobel Peace Prize laureates:

	   1901,Jean Henri Dunant,M
	   1901,Frederic Passy,M
	   1902,Elie Ducommun,M
	   1905,Baroness Bertha	Sophie Felicita	Von Suttner,F
	   1910,Permanent International	Peace Bureau,

     and a second file nobel_nationalities.txt with their nationalities:

	   Jean	Henri Dunant,Switzerland
	   Frederic Passy,France
	   Elie	Ducommun,Switzerland
	   Baroness Bertha Sophie Felicita Von Suttner

     Join the two files	using the second column	from first file	and the	de-
     fault first column	from second file specifying a custom field delimiter:

	   $ join -t, -1 2 nobel_laureates.txt nobel_nationalities.txt
	   Jean	Henri Dunant,1901,M,Switzerland
	   Frederic Passy,1901,M,France
	   Elie	Ducommun,1902,M,Switzerland
	   Baroness Bertha Sophie Felicita Von Suttner,1905,F

     Show only the year	and the	nationality of the laureate using `<<NULL>>'
     to	replace	empty fields:

	   $ join -e "<<NULL>>"	-t, -1 2 -o "1.1 2.2" nobel_laureates.txt nobel_nationalities.txt

     Show only lines from first	file which do not have a match in second file:

	   $ join -v1 -t, -1 2 nobel_laureates.txt nobel_nationalities.txt
	   Permanent International Peace Bureau,1910,

     Assuming a	file named capitals.txt	with the following content:


     Show the name and capital of the country where the	laureate was born.
     This example uses nobel_nationalities.txt as a bridge but does not	show
     any information from that file.  Also see the note	about sort(1) above to
     understand	why we need to sort the	intermediate result.

	   $ join -t, -1 2 -o 1.2 2.2 nobel_laureates.txt nobel_nationalities.txt | \
	       sort -k2	-t, | join -t, -e "<<NULL>>" -1	2 -o 1.1 2.2 - capitals.txt
	   Elie	Ducommun,<<NULL>>
	   Jean	Henri Dunant,<<NULL>>

     For compatibility with historic versions of join, the following options
     are available:

     -a	     In	addition to the	default	output,	produce	a line for each	un-
	     pairable line in both file1 and file2.

     -j1 field
	     Join on the field'th field	of file1.

     -j2 field
	     Join on the field'th field	of file2.

     -j	field
	     Join on the field'th field	of both	file1 and file2.

     -o	list ...
	     Historical	implementations	of join	permitted multiple arguments
	     to	the -o option.	These arguments	were of	the form
	     file_number.field_number as described for the current -o option.
	     This has obvious difficulties in the presence of files named 1.2.

     These options are available only so historic shell	scripts	do not require
     modification and should not be used.

     awk(1), comm(1), paste(1),	sort(1), uniq(1)

     The join command conforms to IEEE Std 1003.1-2001 ("POSIX.1").

FreeBSD	13.0			 June 20, 2020			  FreeBSD 13.0


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