1.3 Suppressing Differences Whose Lines Are All Blank ¶

The --ignore-blank-lines (-B) option ignores changes that consist entirely of blank lines. With this option, for example, a file containing

1.  A point is that which has no part.

2.  A line is breadthless length.
-- Euclid, The Elements, I

is considered identical to a file containing

1.  A point is that which has no part.
2.  A line is breadthless length.


-- Euclid, The Elements, I

Normally this option affects only lines that are completely empty, but if you also specify an option that ignores trailing spaces, lines are also affected if they look empty but contain white space. In other words, -B is equivalent to ‘-I '^$'’ by default, but it is equivalent to -I '^[[:space:]]*$' if -b, -w or -Z is also specified.