V3/usr/man/man1/uniq.1

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NAME		uniq -- report repeated lines in a file
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SYNOPSIS	uniq____ [ -ud___ ]  [ input [ output ] ]
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DESCRIPTION	uniq____
reads the input
file comparing adjacent lines.
In the normal case, the second and succeeding copies
of repeated lines are
removed; the remainder is written on the output file.
Note that repeated lines must be adjacent
in order to be found.
(See sort(I))
If the -u__ flag is used,
just the lines that are not repeated
in the original file are output.
The -d__ option specifies that
one copy of just the repeated lines is to
be written.
Note that the normal mode output is the union of the
-u__ and -d__ mode outputs.
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The following example will print one copy of all
lines in the file a_ that do not occur in b_:
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	sort a x
	uniq x a1
	sort b x
	uniq x b1
	cat a1 b1 >x
	sort x
	uniq -u x >>a1
	sort a1
	uniq -d a1
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FILES		--
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SEE ALSO	sort(I)
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DIAGNOSTICS	"cannot open input", "cannot create output"
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BUGS		--