Commit | Line | Data |
---|---|---|
e6817382 BJ |
1 | .TH JOIN 1 |
2 | .SH NAME | |
3 | join \- relational database operator | |
4 | .SH SYNOPSIS | |
5 | .B join | |
6 | [ | |
7 | options | |
8 | ] | |
9 | file1 file2 | |
10 | .SH DESCRIPTION | |
11 | .I Join | |
12 | forms, on the standard output, | |
13 | a join | |
14 | of the two relations specified by the lines of | |
15 | .I file1 | |
16 | and | |
17 | .IR file2 . | |
18 | If | |
19 | .I file1 | |
20 | is `\-', the standard input is used. | |
21 | .PP | |
22 | .I File1 | |
23 | and | |
24 | .I file2 | |
25 | must be sorted in increasing ASCII collating | |
26 | sequence on the fields | |
27 | on which they are to be joined, | |
28 | normally the first in each line. | |
29 | .PP | |
30 | There is one line in the output | |
31 | for each pair of lines in | |
32 | .I file1 | |
33 | and | |
34 | .I file2 | |
35 | that have identical join fields. | |
36 | The output line normally consists of the common field, | |
37 | then the rest of the line from | |
38 | .IR file1 , | |
39 | then the rest of the line from | |
40 | .IR file2 . | |
41 | .PP | |
42 | Fields are normally separated by blank, tab or newline. | |
43 | In this case, multiple separators count as one, and | |
44 | leading separators are discarded. | |
45 | .PP | |
46 | These options are recognized: | |
47 | .TP | |
48 | .BI \-a n | |
49 | In addition to the normal output, | |
50 | produce a line for each unpairable line in file | |
51 | .IR n , | |
52 | where | |
53 | .I n | |
54 | is 1 or 2. | |
55 | .TP | |
56 | .BI \-e \ s | |
57 | Replace empty output fields by string | |
58 | .IR s . | |
59 | .TP | |
60 | .BI \-j n\ m | |
61 | Join on the | |
62 | .IR m th | |
63 | field of file | |
64 | .IR n . | |
65 | If | |
66 | .I n | |
67 | is missing, use the | |
68 | .IR m th | |
69 | field in each file. | |
70 | .TP | |
71 | .BI \-o \ list | |
72 | Each output line comprises the fields specifed in | |
73 | .IR list , | |
74 | each element of which has the form | |
75 | .IR n . m , | |
76 | where | |
77 | .I n | |
78 | is a file number and | |
79 | .I m | |
80 | is a field number. | |
81 | .PP | |
82 | .TP | |
83 | .BI \-t c | |
84 | Use character | |
85 | .I c | |
86 | as a separator (tab character). | |
87 | Every appearance of | |
88 | .I c | |
89 | in a line is significant. | |
90 | .SH "SEE ALSO" | |
91 | sort(1), comm(1), awk(1) | |
92 | .SH BUGS | |
93 | With default field separation, | |
94 | the collating sequence is that of | |
95 | .IR sort\ \-b ; | |
96 | with | |
97 | .BR \-t , | |
98 | the sequence is that of a plain sort. | |
99 | .PP | |
100 | The conventions of | |
101 | .I join, sort, comm, uniq, look | |
102 | and | |
103 | .IR awk (1) | |
104 | are wildly incongruous. |