join(1)          (Directory and File Management Utilities)          join(1)


   NAME
         join - relational database operator

   SYNOPSIS
         join [ options ] 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 [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 numbered 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.

   EXAMPLE
         The following command line will join the password file and the group
         file, matching on the numeric group ID, and outputting the login
         name, the group name and the login directory.  It is assumed that the


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   join(1)          (Directory and File Management Utilities)          join(1)


         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 commands are
         wildly incongruous.

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




































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