Report or filter out repeated lines in a file.
Reads standard input comparing adjacent lines, and writes a copy of each unique
input line to the standard output. The second and succeeding copies of identical
adjacent input lines are not written. Repeated lines in the input will not be
detected if they are not adjacent, so it may be necessary to sort the files
first.
Syntax
uniq [-c | -d | -u] [-f fields] [-s chars] [input_file [output_file]]
Options
-c Precede each output line with the count of the number of times
the line occurred in the input, followed by a single space.
-d Distinct - Don't output lines that are not repeated in the input.
-f fields
Ignore the first fields in each input line when doing compar-
isons. A field is a string of non-blank characters separated
from adjacent fields by blanks. Field numbers are one based,
i.e. the first field is field one.
-s chars
Ignore the first chars characters in each input line when doing
comparisons. If specified in conjunction with the -f option, the
first chars characters after the first fields fields will be ignored.
Character numbers are one based, i.e. the first character
is character one.
-u Don't output lines that are repeated in the input.
If additional arguments are specified on the command line, the first such argument is used as the name of an input file, the second is used as the name of an output file.
The historic +number and -number options have been deprecated but are still supported in this implementation.
“Do you know what you are? You are a marvel. You are unique” - Pablo Picasso
Related:
uniq man page - Apple.com
sort - Sort text files
