join(1)

     NAME
          join - join lines of two files on a common field

     SYNOPSIS
          join [-a 1|2] [-v 1|2] [-e empty-string] [-o field-list...]
          [-t char] [-j[1|2] field] [-1 field] [-2 field] file1 file2
          join {--help,--version}

     DESCRIPTION
          This documentation is no longer being maintained and may be
          inaccurate or incomplete.  The Texinfo documentation is now
          the authoritative source.

          This manual page documents the GNU version of join.  join
          prints to the standard output a line for each pair of input
          lines, one each from file1 and file2, that have identical
          join fields.  Either filename (but not both) can be `-',
          meaning the standard input.  file1 and file2 should be
          already sorted in increasing order (not numerically) on the
          join fields; unless the -t option is given, they should be
          sorted ignoring blanks at the start of the line, as sort
          does when given the -b option.

          The defaults are: the join field is the first field in each
          line; fields in the input are separated by one or more
          blanks, with leading blanks on the line ignored; fields in
          the output are separated by a space; each output line
          consists of the join field, the remaining fields from file1,
          then the remaining fields from file2.

        OPTIONS
          -a file-number
               Print a line for each unpairable line in file file-
               number (either 1 or 2), in addition to the normal
               output.

          -e string
               Replace empty output fields (those that are missing in
               the input) with string.

          -1, -j1 field
               Join on field field (a positive integer) of file 1.

          -2, -j2 field
               Join on field field (a positive integer) of file 2.

          -j field
               Equivalent to -1 field -2 field.

          -o field-list...
               Construct each output line according to the format in
               field-list.  Each element in field-list consists of a
               file number (either 1 or 2), a period, and a field
               number (a positive integer).  The elements in the list
               are separated by commas or blanks.  Multiple field-list
               arguments can be given after a single -o option; the
               values of all lists given with -o are concatenated
               together.

          -t char
               Use character char as the input and output field
               separator.

          -v file-number
               Print a line for each unpairable line in file file-
               number (either 1 or 2), instead of the normal output.

          In addition, when GNU join is invoked with exactly one
          argument, the following options are recognized:

          --help
               Print a usage message on standard output and exit
               successfully.

          --version
               Print version information on standard output then exit
               successfully.