119 lines
2 KiB
Groff
119 lines
2 KiB
Groff
.\" @(#)join.1 6.1 (Berkeley) 4/29/85
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.\"
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.TH JOIN 1 "April 29, 1985"
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.AT 3
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.SH NAME
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join \- relational database operator
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.SH SYNOPSIS
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.B join
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.RB [ \-a\fIn ]
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.RB [ \-e
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.IR s ]
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.RB [ \-o
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.IR list ]
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.RB [ \-t\fIc ]
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file1 file2
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.SH DESCRIPTION
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.B Join
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forms, on the standard output,
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a join
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of the two relations specified by the lines of
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.I file1
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and
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.IR file2 .
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If
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.I file1
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is `\-', the standard input is used.
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.PP
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.I File1
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and
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.I file2
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must be sorted in increasing ASCII collating
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sequence on the fields
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on which they are to be joined,
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normally the first in each line.
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.PP
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There is one line in the output
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for each pair of lines in
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.I file1
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and
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.I file2
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that have identical join fields.
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The output line normally consists of the common field,
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then the rest of the line from
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.IR file1 ,
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then the rest of the line from
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.IR file2 .
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.PP
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Fields are normally separated by blank, tab or newline.
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In this case, multiple separators count as one, and
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leading separators are discarded.
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.PP
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These options are recognized:
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.TP
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.BI \-a n
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In addition to the normal output,
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produce a line for each unpairable line in file
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.IR n ,
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where
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.I n
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is 1 or 2.
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.TP
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.BI \-e " s"
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Replace empty output fields by string
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.IR s .
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.ig
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.TP
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.BI \-j "n m"
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Join on the
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.IR m th
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field of file
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.IR n .
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If
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.I n
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is missing, use the
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.IR m th
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field in each file.
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..
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.TP
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.BI \-o " list"
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Each output line comprises the fields specified in
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.IR list ,
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each element of which has the form
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.IR n . m ,
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where
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.I n
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is a file number and
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.I m
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is a field number.
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.PP
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.TP
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.BI \-t c
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Use character
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.I c
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as a separator (tab character).
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Every appearance of
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.I c
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in a line is significant.
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.SH "SEE ALSO"
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.BR sort (1),
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.BR comm (1),
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.BR awk (9).
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.SH BUGS
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With default field separation,
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the collating sequence is that of
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.BR "sort \-b" ;
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with
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.BR \-t ,
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the sequence is that of a plain sort.
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.PP
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The conventions of
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.BR join ,
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.BR sort ,
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.BR comm ,
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.BR uniq ,
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.BR look
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and
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.BR awk (9)
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are wildly incongruous.
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.\" ref. to awk(9) man page corrected -- ASW 2005-01-15
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