uniq [OPTION]... [INPUT [OUTPUT]]
Filter adjacent matching lines from INPUT (or standard input), writing
to OUTPUT (or standard output).
With no options, matching lines are merged to the first occurrence.
Mandatory arguments to long options are mandatory for short options
too.
-c, --count
prefix lines by the number of occurrences
-d, --repeated
only print duplicate lines
-D, --all-repeated[=delimit-method]
print all duplicate lines
delimit-method={none(default),prepend,separate} Delimiting is
done with blank lines.
-f, --skip-fields=N
avoid comparing the first N fields
-i, --ignore-case
ignore differences in case when comparing
-s, --skip-chars=N
avoid comparing the first N characters
-u, --unique
only print unique lines
-z, --zero-terminated
end lines with 0 byte, not newline
-w, --check-chars=N
compare no more than N characters in lines
--help display this help and exit
--version
output version information and exit
A field is a run of blanks (usually spaces and/or TABs), then non-blank
characters. Fields are skipped before chars.
Note: ’uniq’ does not detect repeated lines unless they are adjacent.
You may want to sort the input first, or use ‘sort -u’ without ‘uniq’.
Also, comparisons honor the rules specified by ‘LC_COLLATE’.