man/man1/uniq.1

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 UNIQ 1 "May 23, 2021"
 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), sort(1),
attributes(5), environ(5), standards(5)