gistfile1.txt

root@saltmaster:/srv/salt# cat test.sls
create /tmp/foo:
  file.managed:
     - name: /tmp/foo
     - contents: some text

date:
  cmd.run:
    - name: date >> /tmp/foo
    - require:
      - file: create /tmp/foo

append /tmp/foo:
  file.append:
    - name: /tmp/foo
    - text: appended
    - require:
      - cmd: date

gistfile2.txt

root@ceph-storage1:~# cat /tmp/foo
some textFri Aug 30 13:57:55 UTC 2013
appended