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NetBSD 6.1.5 - man page for join (netbsd section 1)

JOIN(1) 			   BSD General Commands Manual				  JOIN(1)

     join -- relational database operator

     join [-a file_number | -v file_number] [-e string] [-j file_number field] [-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 output
     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 options are available:

     -a file_number
		 In addition to the default output, produce a line for each unpairable line in
		 file file_number.  (The argument to -a must not be preceded by a space; see the
		 COMPATIBILITY section.)

     -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 the form
		 'file_number.field', where file_number is a file number and field is a field
		 number.  The elements of list must be either comma (``,'') or whitespace sepa-
		 rated.  (The latter requires quoting to protect it from the shell, or, a simpler
		 approach is to use multiple -o options.)

     -t char	 Use character char as a field delimiter for both input and output.  Every occur-
		 rence 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

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

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

     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 used.

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

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

     -a 	 In addition to the default output, produce a line for each unpairable line in
		 both file 1 and file 2.  (To distinguish between this and -a file_number, join
		 currently requires that the latter not include any white space.)

     -j1 field	 Join on the field'th field of file 1.

     -j2 field	 Join on the field'th field of file 2.

     -j field	 Join on the field'th field of both file 1 and file 2.

     -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 pres-
		 ence of files named ``1.2''.

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

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

     The join command is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.

BSD					  April 28, 1995				      BSD

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