https://groups.google.com/forum/#!msg/ansible-project/JvHfchsgRaU/Vw_CzBbvadgJ
-- code extract ----
# Regexp implementation note:
# - the line to match follows the following pattern:
# - <startofline>: matched by ^
# - A number of white spaces/tabs: matched by \s+
# - the "kernel" string: matched by kernel
# - A list of: <spaces|tab><string> -> this is all the options passed to the kernel
# - possible spaces and tabs at the end : matched by the latest \s*
# - the <end of line>: matched by $
# - the list of: <spaces|tab><string1> described above
# e.g: /vmlinuz-2.6.32-358.el6.x86_64 ro root=/dev/mapper/VolGroup00-root_vol … rd_LVM_LV=VolGroup00/root_vol SYSFONT=latarcyrheb-sun16 rd_NO_DM
# is matched by: (\s+(?!pcie_aspm=off)[\w=/\-\.]+)*
# The (?!pcie_aspm=off) is to direct the regexp engine to check that the string 'pcie_aspm=off'
is not present
# anywhere in the in the <string1> part. This is called negative lookahead.
# This is just a check, no characters are "consumed". The following [\w=/\-\.]+
# is ther to consume aka match any strings made of alphanumeric characters,the '/', the '-', the '.'
# - if the 'pcie_aspm=off' string is present, there is no match
# - the capturing group 1 referred as to \1 in the line= statement
# will capture the whole line but the trailing <withe spaces> and <end of line>
- name: Activate a lacking kernel option 'pcie_aspm=off' in {{ targetgrub }}
lineinfile: dest={{ targetgrub }}
backup=True
backrefs=True
state=present
regexp='(^\s+kernel(\s+(?!pcie_aspm=off)[\w=/\-\.]+)*)\s*$'
line='\1 pcie_aspm=off'
-- end of code extract ----
http://daveops.co.uk/2014/05/using-ansible-to-append-a-string-to-the-end-of-a-line/
http://www.handverdrahtet.org/2016/01/ansible-using-numbered-backreference.html
