Compare two text files. diff reports lines that differ between file1 and file2. Output consists of lines of context from each file, with file1 text flagged by a < symbol and file2 text by a > symbol. Context lines are preceded by the ed command (a, c, or d) that would be used to convert file1 to file2. If one of the files is -, standard input is read. If one of the files is a directory, diff locates the filename in that directory corresponding to the other argument (e.g., diff my_dir junk is the same as diff my_dir/junk junk). If both arguments are directories, diff reports lines that differ between all pairs of files having equivalent names (e.g., olddir/program and newdir/program); in addition, diff lists filenames unique to one directory, as well as subdirectories common to both. See also cmp.
Treat all files as text files. Useful for checking to see if binary files are identical.
Ignore repeating blanks and end-of-line blanks; treat successive blanks as one.
Ignore blank lines in files.
Context diff: print 3 lines surrounding each changed line.
Context diff: print n lines surrounding each changed line. The default context is 3 lines.
To speed up comparison, ignore segments of numerous changes and output a smaller set of changes.
When handling C files, create an output file that contains ...