JOIN(1)             RISC/os Reference Manual              JOIN(1)



NAME
     join - relational database operator

SYNOPSIS
     join [ options ] file1 file2

DESCRIPTION
     join forms, on the standard output, a join of the two rela-
     tions specified by the lines of file1 and file2.  If file1
     is -, the standard input is used.

     file1 and file2 must be sorted in increasing ASCII collating
     sequence on the fields on which they are to be joined, nor-
     mally the first in each line [see sort(1)].

     There is one line in the output for each pair of lines in
     file1 and file2 that have identical join fields.  The output
     line normally consists of the common field, then the rest of
     the line from file1, then the rest of the line from file2.

     The default input field separators are blank, tab, or new-
     line.  In this case, multiple separators count as one field
     separator, and leading separators are ignored.  The default
     output field separator is a blank.

     Some of the options below use the argument n.  This argument
     should be a 1 or a 2 referring to either file1 or file2,
     respectively.  The following options are recognized:

     -an      In addition to the normal output, produce a line
              for each unpairable line in file n, where n is 1 or
              2.

     -e s     Replace empty output fields with string s.

     -jn m    Join on the mth field of file n.  If n is missing,
              use the mth field in each file.  Fields are num-
              bered starting with 1.

     -o list  Each output line includes the fields specified in
              list, each element of which has the form n.m, where
              n is a file number and m is a field number.  The
              common field is not printed unless specifically
              requested.

     -tc      Use character c as a separator (tab character).
              Every appearance of c in a line is significant.
              The character c is used as the field separator for
              both input and output.

INTERNATIONAL FUNCTIONALITY
     join can process characters from supplementary code sets, as



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JOIN(1)             RISC/os Reference Manual              JOIN(1)



     well as ASCII characters.

     Options:

     -e s The string s to be replaced can contain supplementary
          characters.

     -t c The separator c can be a character from the supplemen-
          tary code sets.

EXAMPLE
     The following command line will join the password file and
     the group file, matching on the numeric group ID, and out-
     putting the login name, the group name and the login direc-
     tory.  It is assumed that the files have been sorted in
     ASCII collating sequence on the group ID fields.

       join -j1 4 -j2 3 -o 1.1 2.1 1.6 -t: /etc/passwd /etc/group

SEE ALSO
     awk(1), comm(1), sort(1), uniq(1).

NOTES
     With default field separation, the collating sequence is
     that of sort -b; with -t, the sequence is that of a plain
     sort.

     The conventions of the join, sort, comm, uniq, and awk com-
     mands are wildly incongruous.

     Filenames that are numeric may cause conflict when the -o
     option is used just before listing filenames.























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