JOIN(1)                                                                JOIN(1)



NAME
       join - relational database operator

SYNOPSIS
       join [ options ] file1 file2

DESCRIPTION
       _J_o_i_n  forms, on the standard output, a join of the two relations speci‐
       fied by the lines of _f_i_l_e_1 and _f_i_l_e_2.  If _f_i_l_e_1 is  ‘-’,  the  standard
       input is used.

       _F_i_l_e_1  and  _f_i_l_e_2 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 _f_i_l_e_1 and
       _f_i_l_e_2 that have identical join fields.  The output line  normally  con‐
       sists  of  the common field, then the rest of the line from _f_i_l_e_1, then
       the rest of the line from _f_i_l_e_2.

       Fields are normally separated by blank, tab or newline.  In this  case,
       multiple separators count as one, and leading separators are discarded.

       These options are recognized:

       -a_n    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.

       -j_n _m  Join  on  the _mth field of file _n.  If _n is missing, use the _mth
              field in each file.

       -o _l_i_s_t
              Each output line comprises the fields specified  in  _l_i_s_t,  each
              element  of which has the form _n._m, where _n is a file number and
              _m is a field number.


       -t_c    Use character _c as a separator (tab character).   Every  appear‐
              ance of _c in a line is significant.

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

BUGS
       With  default  field  separation,  the  collating  sequence  is that of
       _s_o_r_t _-_b; with -t, the sequence is that of a plain sort.

       The conventions of _j_o_i_n_, _s_o_r_t_, _c_o_m_m_, _u_n_i_q_, _l_o_o_k and _a_w_k(1)  are  wildly
       incongruous.



7th Edition                     April 29, 1985                         JOIN(1)