File: coreutils.info,  Node: Set operations,  Prev: Header lines,  Up: join invocation

8.3.6 Union, Intersection and Difference of files
-------------------------------------------------

Combine ‘sort’, ‘uniq’ and ‘join’ to perform the equivalent of set
operations on files:

Command                              outcome
--------------------------------------------------------------------------
‘sort -u file1 file2’                Union of unsorted files
                                     
‘sort file1 file2 | uniq -d’         Intersection of unsorted files
                                     
‘sort file1 file1 file2 | uniq -u’   Difference of unsorted files
                                     
‘sort file1 file2 | uniq -u’         Symmetric Difference of unsorted
                                     files
                                     
‘join -t '' -a1 -a2 file1 file2’     Union of sorted files
                                     
‘join -t '' file1 file2’             Intersection of sorted files
                                     
‘join -t '' -v2 file1 file2’         Difference of sorted files
                                     
‘join -t '' -v1 -v2 file1 file2’     Symmetric Difference of sorted
                                     files
                                     

   All examples above operate on entire lines and not on specific
fields: ‘sort’ without ‘-k’ and ‘join -t ''’ both consider entire lines
as the key.