join(1) join(1)
join - relational database operator
join [ -a n | -v n ] [ -e s ] [ -o list ] [ -t c ] [ -1 field ] [ -2
field ] file1 file2
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 code set collating
sequence on the fields on which they are to be joined, normally the first
in each line [see sort(1)]. join processes supplementary code set
characters in files, and recognizes supplementary code set characters
given to the -e and -t options (see below) according to the locale
specified in the LC_CTYPE environment variable [see LANG on environ(5)].
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:
-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 with string s. s may contain
supplementary code set characters.
-o list Each output line includes the fields specified in list, each
element of which has the form n<b>.m, where n is a file number and
m is a field number. The common field is not printed unless
specifically requested. The list must be a single command line
argument.
-t c 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. c may be
a supplementary code set character.
-v n Instead of the default output, produce a line only for each
unpairable line in n, where n is 1 or 2. If both -v 1 and -v 2
are specified, all unpairable lines will be output.
Page 1
join(1) join(1)
-1 field Join the fieldth field of file 1. Fields are decimal integers
starting with 1.
-2 field Join the fieldth field of file 2. Fields are decimal integers
starting with 1.
The following options are obsoleted:
-j field
Equivalent to: -1 field -2 field.
-j1 field
Equivalent to: -1 field.
-j2 field
Equivalent to: -2 field.
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 files
have been sorted in code set collating sequence on the group ID fields.
join -1 4 -2 3 -o 1.1,2.1,1.6 -t : /etc/passwd /etc/group
/usr/lib/locale/locale<b>/LC_MESSAGES/uxdfm
language-specific message file [See LANG on environ(5).]
awk(1), comm(1), sort(1), uniq(1)
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.
As an obsolescent feature, mutiple arguments can be specified for -o
option. At that time, filenames that are numeric may cause conflict when
the -o option is used just before listing filenames.
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