1.2 Suppressing Differences in Blank and Tab Spacing

The ‘-E’ and ‘--ignore-tab-expansion’ options ignore the distinction between tabs and spaces on input. A tab is considered to be equivalent to the number of spaces to the next tab stop. diff assumes that tab stops are set every 8 print columns.

The ‘-b’ and ‘--ignore-space-change’ options are stronger. They ignore white space at line end, and consider all other sequences of one or more white space characters to be equivalent. With these options, diff considers the following two lines to be equivalent, where ‘$’ denotes the line end:

Here lyeth  muche rychnesse  in lytell space.   -- John Heywood$
Here lyeth muche rychnesse in lytell space. -- John Heywood   $

The ‘-w’ and ‘--ignore-all-space’ options are stronger still. They ignore difference even if one file has white space where the other file has none. White space characters include tab, newline, vertical tab, form feed, carriage return, and space; some locales may define additional characters to be white space. With these options, diff considers the following two lines to be equivalent, where ‘$’ denotes the line end and ‘^M’ denotes a carriage return:

Here lyeth  muche  rychnesse in lytell space.--  John Heywood$
  He relyeth much erychnes  seinly tells pace.  --John Heywood   ^M$