Unified diff example `diff -u alice.txt bob.txt > unified-diff.txt`

alice.txt

Alice was beginning to get very tired of sitting by her sister on the
bank, and of having nothing to do: once or twice she had peeped into the
book her sister was reading, but it had no pictures or conversations in
it, 'and what is the use of a book,' thought Alice 'without pictures or
conversation?'

bob.txt

Bob was beginning to get very tired of sitting by her sister on the
bank, and of having nothing to do: once or twice she had peeped into the
book her sister was reading, but it had no pictures or conversations in
it, 'and what is the use of a book,' thought Bob 'without pictures or
pages or
conversation?'

unified-diff.diff

--- alice.txt	Mon May 27 11:20:01 2013
+++ bob.txt	Mon May 27 11:21:14 2013
@@ -1,5 +1,6 @@
-Alice was beginning to get very tired of sitting by her sister on the
+Bob was beginning to get very tired of sitting by her sister on the
 bank, and of having nothing to do: once or twice she had peeped into the
 book her sister was reading, but it had no pictures or conversations in
-it, 'and what is the use of a book,' thought Alice 'without pictures or
+it, 'and what is the use of a book,' thought Bob 'without pictures or
+pages or
 conversation?'