uniq display unique lines of sorted file	Command
	SYNOPSIS DESCRIPTION   Options EXAMPLES DIAGNOSTICS PORTABILITY SEE ALSO

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SYNOPSIS

uniq [-c|-d|-u] [-f number1] [-s number2] [input_file [output_file]]

uniq [-c|-d|-u] [-number] [+number] [input_file [output_file]]

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DESCRIPTION

uniq manipulates lines which occur more than once in a file. The file must be sorted, since uniq only compares adjacent lines. When you invoke this command with no options, it writes only one copy of each line in input_file to output_file. If you do not specify input_file or you specify -, uniq reads the standard input. If you do not specify output_file, uniq uses the standard output.

Options

-c

precedes each output line with the number of times that line occurred in the input.

-d

displays only lines which are repeated (one copy of each line).

-f number1

ignores the first number1 fields when comparing lines. Blanks separate fields in the input.

-s number2

ignores the first number2 characters when comparing lines. If you specify both -s and -f, uniq ignores the first number2 characters after the first number1 fields.

-u

displays only those lines which are not repeated.

You may choose only one of the -c, -d, or -u options.

-number

is an obsolete equivalent to -f number.

+number

is an obsolete equivalent to -s number.

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EXAMPLES

uniq

is a filter which prints one copy of each different line in its sorted input.

uniq -f 2 -s 1

compares lines starting with the 2nd character of the 3rd field.

uniq -d

outputs one instance of each repeated line in the input (and omits all unique lines).

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DIAGNOSTICS

Possible exit status values are:

0

Successful completion.

1

Failure due to any of the following:

— invalid command line option

— missing number after -f

— missing or invalid number after -s

— inability to open the input or output file

Missing character skip count

You specified -s but did not supply a number after the -s.

Missing number of fields to skip

You specified -f but did not supply a number after the -f.

field skip not a number in "string"

In a -number or +number construct, number wasn't valid. This could arise from a typo when entering a - option.

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PORTABILITY

POSIX.2. x/OPEN Portability Guide 4.0.

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SEE ALSO

Commands:

comm, sort