join - relational database operator
join [-a filenumber | -v filenumber] [-1 fieldnumber] [-
2 fieldnumber] [-o list] [-e string] [-t char] file1 file2
join [-a filenumber] [-j fieldnumber] [-j1 fieldnumber] [-
j2 fieldnumber] [-o list] [-e string] [-t char] file1 file2
The join command forms, on the standard output, a join of
the two relations specified by the lines of file1 and file2.
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.
This format can be changed by using the -o option (see
below). The -a option can be used to add unmatched lines to
the output. The -v option can be used to output only
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.
If the input files are not in the appropriate collating
sequence, the results are unspecified.
Some of the options below use the argument filenumber. This
argument should be a 1 or a 2 referring to either file1 or
In addition to the normal output, produce a line for
each unpairable line in file filenumber, where
filenumber is 1 or 2. If both -a 1 and -a 2 are speci-
fied, all unpairable lines will be output.
Replace empty output fields in the list selected by
option -o with the string string.
Equivalent to -1fieldnumber -2fieldnumber.
Equivalent to -1fieldnumber.
Equivalent to -2fieldnumber. Fields are numbered
starting with 1.
Each output line includes the fields specified in
list. Fields selected by list that do not appear in
the input will be treated as empty output fields. (See
the -e option.) Each element of which has the either
the form filenumber.fieldnumber, or 0, which
represents the join field. The common field is not
printed unless specifically requested.
Use character char as a separator. Every appearance of
char in a line is significant. The character char is
used as the field separator for both input and output.
With this option specified, the collating term should
be the same as sort without the -b option.
Instead of the default output, produce a line only for
each unpairable line in filenumber, where filenumber
is 1 or 2. If both -v 1 and -v 2 are specified, all
unpairable lines will be output.
Join on the fieldnumberth field of file 1. Fields are
decimal integers starting with 1.
Join on the fieldnumberth field of file 2. Fields are
decimal integers starting with 1.
The following operands are supported:
file2 A path name of a file to be joined. If either of the
file1 or file2 operands is -, the standard input is
used in its place.
file1 and file2 must be sorted in increasing collating
sequence as determined by LC_COLLATE on the fields on which
they are to be joined, normally the first in each line (see
See largefile(5) for the description of the behavior of join
when encountering files greater than or equal to 2 Gbyte (2
Example 1: Joining the password file and group file
The following command line will join the password file and
the group file, matching on the numeric group ID, and out-
putting the login name, the group name and the login direc-
tory. It is assumed that the files have been sorted in ASCII
collating sequence on the group ID fields.
example% join -j1 4-j2 3 -o 1.1 2.1 1.6 -t:/etc/passwd /etc/group
Example 2: Using the -o option
The -o 0 field essentially selects the union of the join
fields. For example, given file phone:
!Name Phone Number
Don +1 123-456-7890
Hal +1 234-567-8901
Yasushi +2 345-678-9012
and file fax:
!Name Fax Number
Don +1 123-456-7899
Keith +1 456-789-0122
Yasushi +2 345-678-9011
where the large expanses of white space are meant to each
represent a single tab character), the command:
example% join -t"tab" -a 1 -a 2 -e '(unknown)' -o 0,1.2,2.2 phone fax
!Name Phone Number Fax Number
Don +1 123-456-7890 +1 123-456-7899
Hal +1 234-567-8901 (unknown
Keith (unknown) +1 456-789-012
Yasushi +2 345-678-9012 +2 345-678-9011
See environ(5) for descriptions of the following environment
variables that affect the execution of join: LANG, LC_ALL,
LC_CTYPE, LC_MESSAGES, LC_COLLATE, and NLSPATH.
The following exit values are returned:
0 All input files were output successfully.
>0 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
| CSI | Enabled |
| Interface Stability | Standard |
awk(1), comm(1), sort(1), uniq(1), attributes(5),
environ(5), largefile(5), standards(5)
With default field separation, the collating sequence is
that of sort -b; with -t, the sequence is that of a plain
The conventions of the join, sort, comm, uniq, and awk com-
mands are wildly incongruous.
Man(1) output converted with