1. Computing
Linux / Unix Command: uniq
Command Library
NAME
uniq (removes duplicate lines from a uniqed file)
SYNOPSIS
uniq [-cdu] [-f skip-fields] [-s skip-chars] [-w check-chars] [-#skip-fields] [+#skip-chars] [--count] [--repeated] [--unique] [--skip-fields=skip-fields] [--skip-chars=skip-chars] [--check-hars=check-chars] [--help] [--version] [infile] [outfile]
DESCRIPTION
uniq prints the unique lines in a sorted file, retaining only one of a run of matching lines. Optionally, it can show only lines that appear exactly once, or lines that appear more than once. uniq requires sorted input since it compares only consecutive lines.
OPTIONS
-u, --unique
Only print unique lines.

-d, --repeated
Only print duplicate lines.

-c, --count
Print the number of times each line occurred along with the line.

-number, -f, --skip-fields=number
In this option, number is an integer representing the number of fields to skip over before checking for uniqueness. The first number fields, along with any blanks found before number fields is reached, are skipped over and not counted. Fields are defined as a strings of non-space, non-tab characters, that are separated from each other by spaces and tabs.

+number, -s, --skip-chars=number
In this option, number is an integer representing the number of characters to skip over before checking for uniqueness. The first number characters, along with any blanks found before number characters is reached, are skipped over and not counted. If you use both the field and character skipping options, fields are skipped over first.

-w, --check-chars=number
Specify the number of characters to compare in the lines, after skipping any specified fields and characters. Normally the entire rest of the lines are compared.

--help
Print a usage message and exit with a status code indicating success.

--version
Print version information on standard output then exit.

EXAMPLE

% sort myfile | uniq

eliminates duplicate lines from the stream (the symbol "|" pipes the output from sort myfile to the uniq command).

Important: Use the man command (% man) to see how a command is used on your particular computer.

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