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(textutils.info)join invocation


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`join': Join lines on a common field
====================================

   `join' writes to standard output a line for each pair of input lines
that have identical join fields.  Synopsis:

     join [OPTION]... FILE1 FILE2

   Either FILE1 or FILE2 (but not both) can be `-', meaning standard
input.  FILE1 and FILE2 should be already sorted in increasing textual
order on the join fields, using the collating sequence specified by the
`LC_COLLATE' locale.  Unless the `-t' option is given, the input should
be sorted ignoring blanks at the start of the join field, as in `sort
-b'.  If the `--ignore-case' option is given, lines should be sorted
without regard to the case of characters in the join field, as in `sort
-f'.

   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.

   The program accepts the following options.  Also see Note: Common
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 those output fields that are missing in the input with
     STRING.

`-i'
`--ignore-case'
     Ignore differences in case when comparing keys.  With this option,
     the lines of the input files must be ordered in the same way.  Use
     `sort -f' to produce this ordering.

`-1 FIELD'
`-j1 FIELD'
     Join on field FIELD (a positive integer) of file 1.

`-2 FIELD'
`-j2 FIELD'
     Join on field FIELD (a positive integer) of file 2.

`-j FIELD'
     Equivalent to `-1 FIELD -2 FIELD'.

`-n'
     Use numerical order when joining FILE1 and FILE2.  They must be
     sorted numerically beforehand.

`-o FIELD-LIST...'
     Construct each output line according to the format in FIELD-LIST.
     Each element in FIELD-LIST is either the single character `0' or
     has the form M.N where the file number, M, is `1' or `2' and N is
     a positive field number.

     A field specification of `0' denotes the join field.  In most
     cases, the functionality of the `0' field spec may be reproduced
     using the explicit M.N that corresponds to the join field.
     However, when printing unpairable lines (using either of the `-a'
     or `-v' options), there is no way to specify the join field using
     M.N in FIELD-LIST if there are unpairable lines in both files.  To
     give `join' that functionality, POSIX invented the `0' field
     specification notation.

     The elements in FIELD-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.  All output lines - including those printed because of
     any -a or -v option - are subject to the specified FIELD-LIST.

`-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,
options `--help' and `--version' are recognized.  Note: Common
options.


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