![]() ![]() There are a few OSes out there which don't have a newline character, but instead have fixed- or variable-sized records on these systems, the mapping from files to C source introduces a \n at the end of each record. On DOS and Windows, each CR LF sequence ( \r\n) is mapped to a newline ( \n this is what always happens when reading a file opened as text on these OSes). On unix systems, the mapping is straightforward. More precisely, a translation unit is viewed in an implementation-defined as a series of lines, each of which must end with a newline character ( n1256 §5.1.1.1). So diff uses this special text \ No newline at end of file to differentiate a file that didn't end in a newline from a file that did.īy the way, in a C context, a source file similarly consists of a series of lines. Since diff is line-oriented, it can't indicate this by storing a newline for one of the files but not for the others - the newlines are necessary to indicate where each line in the diff file starts and ends. With GNU diff, if one of the files being compared ends with a newline but not the other, it is careful to note that fact. GNU utilities have a policy of behaving decently with non-text files, and so do most other modern utilities, but you may still encounter odd behavior with files that are missing a final newline¹. Utilities that are supposed to operate on text files may not cope well with files that don't end with a newline historical Unix utilities might ignore the text after the last newline, for example. A file that is not empty and does not end with a newline is therefore not a text file. It's not about adding an extra newline at the end of a file, it's about not removing the newline that should be there.Ī text file, under unix, consists of a series of lines, each of which ends with a newline character ( \n). ![]()
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