UNIQ(1) User Commands UNIQ(1)


NAME


uniq - report or filter out repeated lines in a file

SYNOPSIS


/usr/bin/uniq
/usr/bin/uniq [-c | -d | -u] [-f fields] [-s char]
[input_file [output_file]]


/usr/bin/uniq [-c | -d | -u] [-n] [+ m] [input_file [output_file]]


ksh93
uniq [-cdiu] [-D[delimit]] [-f fields] [-s chars] [-w chars]
[input_file [output_file]]


uniq [-cdiu] [-D[delimit]] [-n] [+m] [-w chars] [input_file [output_file]]


DESCRIPTION


/usr/bin/uniq
The uniq utility reads an input file comparing adjacent lines and writes
one copy of each input line on the output. The second and succeeding
copies of repeated adjacent input lines are not written.


Repeated lines in the input are not detected if they are not adjacent.

ksh93
The uniq built-in in ksh93 is associated with the /bin or /usr/bin path.
It is invoked when uniq is executed without a pathname prefix and the
pathname search finds a /bin/uniq or /usr/bin/uniq executable.


uniq reads an input, comparing adjacent lines, and writing one copy of
each input line on the output. The second and succeeding copies of the
repeated adjacent lines are not written.


If output_file is not specified, uniq writes to standard output. If
input_file is not specified, or if input_file is -, uniq reads from
standard input, and the start of the file is defined as the current
offset.

OPTIONS


/usr/bin/uniq
The following options are supported by /usr/bin/uniq:

-c
Precedes each output line with a count of the number of
times the line occurred in the input.


-d
Suppresses the writing of lines that are not repeated in the
input.


-f fields
Ignores the first fields fields on each input line when
doing comparisons, where fields is a positive decimal
integer. A field is the maximal string matched by the basic
regular expression:

[[:blank:]]*[^[:blank:]]*


If fields specifies more fields than appear on an input
line, a null string is used for comparison.


+m
Equivalent to -s chars with chars set to m.


-n
Equivalent to -f fields with fields set to n.


-s chars
Ignores the first chars characters when doing comparisons,
where chars is a positive decimal integer. If specified in
conjunction with the -f option, the first chars characters
after the first fields fields is ignored. If chars specifies
more characters than remain on an input line, a null string
is used for comparison.


-u
Suppresses the writing of lines that are repeated in the
input.


ksh93
The following options are supported by the uniq built-in command is
ksh93:

-c
--count
Outputs the number of times each line
occurred along with the line.


-d
--repeated | duplicates
Outputs only duplicate lines.


-D
--all-repeated[=delimit]
Outputs all duplicate lines as a group with
an empty line delimiter specified by delimit.

Specify delimit as one of the following:

none
Do not delimit duplicate groups.


prepend
Prepend an empty line before each
group.


separate
Separate each group with an empty
line.

The value for delimit can be omitted. The
default value is none.


-f
--skip-fields=fields
Skips over fields number of fields before
checking for uniqueness. A field is the
minimal string matching the BRE
[[:blank:]]*[^[:blank:]]*.


-i
--ignore-case
Ignore case in comparisons.


+m
Equivalent to the -s chars option, with chars
set to m.


-n
Equivalent to the -f fields option, with
fields set to n.


-s
--skip-chars=chars
Skips over chars number of characters before
checking for uniqueness.

If specified with the -f option, the first
chars after the first fields are ignored. If
the chars specifies more characters than are
on the line, an empty string is used for
comparison.


-u
--uniq
Outputs unique lines.


-w
--check-chars=chars
Skips over any specified fields and
characters, then compares chars number of
characters.


OPERANDS


The following operands are supported:

input_file
A path name of the input file. If input_file is not
specified, or if the input_file is -, the standard input
is used.


output_file
A path name of the output file. If output_file is not
specified, the standard output is used. The results are
unspecified if the file named by output_file is the file
named by input_file.


EXAMPLES


Example 1: Using the uniq Command




The following example lists the contents of the uniq.test file and
outputs a copy of the repeated lines.


example% cat uniq.test
This is a test.
This is a test.
TEST.
Computer.
TEST.
TEST.
Software.

example% uniq -d uniq.test
This is a test.
TEST.
example%


The next example outputs just those lines that are not repeated in the
uniq.test file.


example% uniq -u uniq.test
TEST.
Computer.
Software.
example%


The last example outputs a report with each line preceded by a count of
the number of times each line occurred in the file:


example% uniq -c uniq.test
2 This is a test.
1 TEST.
1 Computer.
2 TEST.
1 Software.
example%


ENVIRONMENT VARIABLES


See environ(5) for descriptions of the following environment variables
that affect the execution of uniq: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.

EXIT STATUS


The following exit values are returned:

0
Successful completion.


>0
An error occurred.


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:

/usr/bin/uniq

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|CSI | Enabled |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(5). |
+--------------------+-------------------+

ksh93

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+


The ksh93 built-in binding to /bin and /usr/bin is Volatile. The built-
in interfaces are Uncommitted.

SEE ALSO


comm(1), ksh93(1), , pcat(1), sort(1), uncompress(1), attributes(5),
environ(5), standards(5)


March 13, 2008 UNIQ(1)