/usr/bin/uniq

Usage: /usr/bin/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, one for each group
  -D
         print all duplicate lines
      --all-repeated[=METHOD]
         like -D, but allow separating groups with an empty line;
         METHOD={none(default),prepend,separate}
  -f, --skip-fields=N
         avoid comparing the first N fields
      --group[=METHOD]
         show all items, separating groups with an empty line;
         METHOD={separate(default),prepend,append,both}
  -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
         line delimiter is NUL, 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.

'uniq' does not detect repeated lines unless they are adjacent.
You may want to sort the input first, or use 'sort -u' without 'uniq'.

Report bugs to: <bug-coreutils@gnu.org>.
GNU coreutils home page: <https://www.gnu.org/software/coreutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>
Full documentation <https://www.gnu.org/software/coreutils/uniq>
or available locally via: info '(coreutils) uniq invocation'