diff - print differences between two files

     diff   [-c | -e | -C n] [-br]file1 file2


     -C n Produce output that contains n lines of context

     -b   Ignore white space when comparing

     -c   Produce output that contains three lines of context

     -e   Produce an ed-script to convert file1 into file2

     -r   Apply diff recursively to files and directories of  the  same  name,
          when file1 and file2 are both directories


     diff file1 file2    # Print differences between 2 files

     diff -C 0 file1 file2
                         # Same as above

     diff -C 3 file1 file2
                         # Output three lines of context with every difference

     diff -c file1 file2 # Same

     diff /etc /dev      # Compares recursively the directories /etc and /dev

     diff passwd /etc    # Compares ./passwd to /etc/passwd


     Diff compares two files and generates a list of lines telling how the two
     files  differ.   Lines may not be longer than 128 characters.  If the two
     arguments on the command line  are  both  directories,  diff  recursively
     steps  through  all subdirectories comparing files of the same name. If a
     file name is found only in one directory, a diagnostic message is written
     to  stdout.  A file that is of either block special, character special or
     FIFO special type, cannot be compared to any other file.   On  the  other
     hand,  if  there is one directory and one file given on the command line,
     diff tries to compare the  file  with  the  same  name  as  file  in  the
     directory directory.

     cdiff(1), cmp(1), comm(1), patch(1).