4 join \- relational database operator
13 forms, on the standard output,
15 of the two relations specified by the lines of
19 If one of the file names is
21 the standard input is used.
26 must be sorted in increasing
29 sequence on the fields
30 on which they are to be joined,
31 normally the first in each line.
33 There is one line in the output
34 for each pair of lines in
38 that have identical join fields.
39 The output line normally consists of the common field,
40 then the rest of the line from
42 then the rest of the line from
45 Input fields are normally separated spaces or tabs;
46 output fields by space.
47 In this case, multiple separators count as one, and
48 leading separators are discarded.
50 The following options are recognized, with POSIX syntax.
53 In addition to the normal output,
54 produce a line for each unpairable line in file
63 omitting output for paired lines.
66 Replace empty output fields by string
82 Archaic equivalent for
86 Each output line comprises the designated fields.
87 The comma-separated field designators are either
89 meaning the join field, or have the form
96 Archaic usage allows separate arguments for field designators.
102 as the only separator (tab character) on input and output.
105 in a line is significant.
109 sort -t: +1 /adm/users | join -t: -1 2 -a 1 -e "" - bdays
112 file, leaving unknown
119 contains sorted lines like
120 .LR "ken:Feb\ 4,\ 1953" .
123 tr : ' ' </adm/users | sort -k 3 3 >temp
128 join -1 3 -2 3 -o 1.1,2.1 temp temp | awk '$1 < $2'
129 Print all pairs of users with identical userids.
131 .B /sys/src/cmd/join.c
137 With default field separation,
138 the collating sequence is that of
143 the sequence is that of
147 One of the files must be randomly accessible.