JOIN(1) | General Commands Manual | JOIN(1) |
join
— relational
database operator
join |
[-a file_number |
-v file_number]
[-e string]
[-j file_number field]
[-o list]
[-t char]
[-1 field]
[-2 field]
file1 file2 |
The join utility performs an ``equality join'' on the specified files and writes the result to the standard output. The ``join field'' is the field in each file by which the files are compared. The first field in each line is used by default. There is one line in the output for each pair of lines in file1 and file2 which have identical join fields. Each output line consists of the join field, the remaining fields from file1 and then the remaining fields from file2.
The default field separators are tab and space characters. In this case, multiple tabs and spaces count as a single field separator, and leading tabs and spaces are ignored. The default output field separator is a single space character.
Many of the options use file and field numbers. Both file numbers and field numbers are 1 based, i.e. the first file on the command line is file number 1 and the first field is field number 1. The following options are available:
-a
file_number-a
must not be preceded by a space; see the
COMPATIBILITY section.)-e
string-o
list-o
option specifies the fields that will be
output from each file for each line with matching join fields. Each
element of list has the form
‘file_number.field
’, where
file_number is a file number and
field is a field number. The elements of list must
be either comma (``,'') or whitespace separated. (The latter requires
quoting to protect it from the shell, or, a simpler approach is to use
multiple -o
options.)-t
char-v
file_number-v
1 and
-v
2 may be specified at the
same time.-1
field-2
fieldWhen the default field delimiter characters are used, the files to
be joined should be ordered in the collating sequence of
sort(1), using the
-b
option, on the fields on which they are to be
joined, otherwise join
may not report all field
matches. When the field delimiter characters are specified by the
-t
option, the collating sequence should be the same
as sort(1) without the
-b
option.
If one of the arguments file1 or file2 is ``-'', the standard input is used.
The join
utility exits 0 on
success, and >0 if an error occurs.
For compatibility with historic versions of
join
, the following options are available:
-a
-a
file_number,
join
currently requires that the latter not
include any white space.)-j1
field-j2
field-j
field-o
list ...join
permitted
multiple arguments to the -o
option. These
arguments were of the form ``file_number.field_number'' as described for
the current -o
option. This has obvious
difficulties in the presence of files named ``1.2''.These options are available only so historic shell scripts don't require modification and should not be used.
The join
command is expected to be
IEEE Std 1003.2 (“POSIX.2”)
compatible.
April 28, 1995 | NetBSD 10.99 |