Sed example: update a value in a block of a config file

Sed example for updating a value in a block in a config file

Thanks to Jason Montleon for the example

[jmontleo@jmontleo ~]$ cat alpha.txt 
[lazy]
#enabled: false

[foo]
#enabled: false
[jmontleo@jmontleo ~]$ sed -i '/^\[lazy\]$/{$!{N;s/^\[lazy\]\n#enabled: false$/[lazy]\n#enabled: true/;ty;P;D;:y}}' alpha.txt
[jmontleo@jmontleo ~]$ cat alpha.txt 
[lazy]
#enabled: true

[foo]
#enabled: false

Reference: http://unix.stackexchange.com/questions/26284/how-can-i-use-sed-to-replace-a-multi-line-string