4.2BSD/usr/man/man1/uniq.1

.TH UNIQ 1  "10 February 1983"
.SH NAME
uniq \- report repeated lines in a file
.SH SYNOPSIS
.B uniq
[
.B \-udc
[
.BR + n
] [
.BR \- n
]
] [ input [ output ] ]
.SH DESCRIPTION
.I 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
.IR  sort (1).
If the
.B \-u
flag is used, just the lines that are not repeated
in the original file are output.  The
.B \-d
option specifies that one copy of just the repeated lines is to be written.
The normal mode output is the union of the
.B \-u
and
.B \-d
mode outputs.
.PP
The
.B \-c
option supersedes
.B \-u
and
.B \-d
and generates an output report in default style
but with each line preceded by a count of the number of times it occurred.
.PP
The
.I n
arguments specify skipping an initial portion of each line in the comparison:
.TP 8
.BI \- n
The first
.IR n 
fields together with any blanks before each are ignored.
A field is defined as a string of non-space, non-tab characters
separated by tabs and spaces from its neighbors.
.TP 8
.BI + n
The first
.IR n 
characters are ignored.  Fields are skipped before characters.
.PP
.SH "SEE ALSO"
sort(1), comm(1)