Sort and remove duplicate lines from two (or more files). Display only uniq lines from files.

1 
 $ sort file1 file2 | uniq -u

March 6, 2013, 8:58 a.m. — EvaggelosBalaskas

Explanation

The -u flag of uniq removes duplicate lines from the input.

Example file1:

123456
234567
345678

Example file2:

234567
345678
456789

Result:

123456
456789