nauniq – remove non-adjacent duplicate lines

nauniq is a command-line utility that identifies repeated lines even when they are separated by other records in the input.

The standard uniq command only detects consecutive duplicate lines. nauniq instead maintains information about previously encountered records, allowing it to filter repeated entries without sorting the source data.

The application provides several options for controlling how records are compared and how much information is retained in memory. Users can limit the number of remembered entries, compare selected portions of each line or store hashes instead of complete records.

It can also maintain a file containing unique records by appending only previously unseen entries. This makes it useful for collecting output from commands that may repeatedly produce the same information.

This is free and open source software.

Key Features

• Identifies duplicate lines even when they are not adjacent.
• Print only unique records or use –repeated to output duplicate records.
• Case-insensitive comparisons with –ignore-case.
• Limit the number of remembered entries using –num-entries to control memory consumption.
• Skip a specified number of leading characters when comparing records.
• Limit comparisons to a specified number of characters.
• Store MD5 hashes instead of complete lines to reduce memory usage for long records.
• Forget previously encountered entries when a specified regular expression matches.
• Append new records to an existing output file while checking its previous contents.
• Supports input and output filenames as command-line arguments.

Website: metacpan.org
Support: GitHub Code Repository
Developer: perlancar
License: Same terms as Perl 5 (Artistic License 1.0 or GNU General Public License v1.0)

nauniq is written in Perl. Learn Perl with our recommended free books and free tutorials.

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