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.
For context and unified diff, print n lines of context. Same as specifying a number with -C or -U.
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 three lines surrounding each changed line.
Context diff: print n lines surrounding each changed line. The default context is three lines.
Ignore segments of numerous changes and output a smaller set of changes.