join(1)                                                   join(1)



     NAME
          join - relational database operator

     SYNOPSIS
          join [-an] [-e string] [-jn m] [-o list] [-tc] file1 file2

     DESCRIPTION
          join forms, on the standard output, a join of the two
          relations 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,
          normally the first in each line.

          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
          newline.  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 below flag options use the argument n.  This
          argument should be a 1 or a 2 referring to either file1 or
          file2, respectively.  The following flag 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 by 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
                   numbered starting with 1.

          -o list  Each output line comprises 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.

     EXAMPLE



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     join(1)                                                   join(1)



          If file1 contains:

               Austen -
               Bailey -
               Clark -
               Dawson -
               Smith -

          and file2 contains:

               Austen Jack Anchor Brewery
               Clark Maryann Shoeshop
               Daniels Steve Computer Software
               Dawson Sylvia Toot Sweets
               Smith Sally Talcum Powdery

          then

          join -j1 1 -j2 1 -o 2.2 2.1 1.2 2.3 2.4 file1 file2

          will generate

               Jack Austen - Anchor Brewery
               Maryann Clark - Shoeshop
               Sylvia Dawson - Toot Sweets
               Sally Smith - Talcum Powdery

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

          joins the password file and the group file, matching on the
          numeric group ID, and the login name, the group name, and
          the login directory. It is assumed that the files have been
          sorted in ASCII collating sequence on the group ID fields.

     FILES
          /usr/bin/join

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

     BUGS
          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 join(1), sort(1), comm(1), uniq (1) and
          awk(1) are wildly incongruous.

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




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