Sometimes mailers, editors, or other programs change spaces into tabs, or vice versa. If this happens to a patch file or an input file, the files might look the same, but patch will not be able to match them properly. If this problem occurs, use the -l or --ignore-white-space option, which makes patch compare blank characters (i.e. spaces and tabs) loosely so that any nonempty sequence of blanks in the patch file matches any nonempty sequence of blanks in the input files. Non-blank characters must still match exactly. Each line of the context must still match a line in the input file.