uniq is as specified in the Single UNIX Specification but with differences as listed below.
The behaviors specified in this section are expected to disappear from a future version of the LSB; applications should only use the non-LSB-deprecated behaviors.
is equivalent to -c.
is equivalent to -d.
prints all duplicate lines.
is equivalent to -f fields.
ignores differences in case when comparing.
is equivalent to -s.
is equivalent to -u.
compares no more than N characters in lines.
outputs version information and exits.