40 lines
1.0 KiB
Groff
40 lines
1.0 KiB
Groff
.Dd January 30, 2015
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.Dt UNIQ 1
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.Os
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.Sh NAME
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.Nm uniq
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.Nd report or filter out repeated lines in a file
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.Sh SYNOPSIS
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.Nm
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.Op Fl cdu
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.Op Ar file
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.Sh DESCRIPTION
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.Nm
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reads file and writes one copy of a line from each group of consecutive
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duplicate lines to stdout. If no file is given, uniq reads from stdin.
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.Sh OPTIONS
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.Bl -tag -width Ds
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.It Fl c
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prefixes each line with a count of its consecutive occurrences in the input.
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.It Fl d
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suppresses non-duplicate lines (thus 'uniq -d' prints only duplicates).
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.It Fl u
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suppresses non-unique lines (thus 'uniq -u' prints only uniques).
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.El
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.Sh BUGS
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The original sbase implementation of
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.Nm
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supported multiple input-file arguments as e.g.
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.Xr cat 1
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and
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.Xr grep 1
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do.
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Unfortunately, POSIX uniq treats its second argument (if present) as an
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output filename and clobbers it. Since users and scripts which rely on
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.Nm
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supporting multiple input-file arguments would be at risk of data loss
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if they ever ran into a POSIX-compatible
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.Nm
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, support for multiple input-file arguments was removed from this
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implementation.
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