Unable to change config file with sed using groups and multiple lines

Question

I'm trying to script changes in a config file (/var/lib/polkit-1/localauthority/10-vendor.d/com.ubuntu.desktop.pkla), which boils down to:

[Update already installed software]
Identity=unix-group:admin;unix-group:sudo
Action=org.debian.apt.upgrade-packages
ResultActive=yes

[Printer administration]
Identity=unix-group:lpadmin;unix-group:admin;unix-group:sudo
Action=org.opensuse.cupspkhelper.mechanism.*
ResultActive=yes

[Disable hibernate by default in upower]
Identity=unix-user:*
Action=org.freedesktop.upower.hibernate
ResultActive=no

I'm trying to set ResultActive=yes for all blocks that start with [Disable hibernate. Using sed and regex groups I came up with:

sed -i 's/\(Disable hibernate.*\n.*\n.*\nResultActive\=\)no/\1yes/' /var/lib/polkit-1/localauthority/10-vendor.d/com.ubuntu.desktop.pkla

However this does not change the file. According to regexr, the regex matches, but checking with sed.js.org, sed doesn't change a thing.

How can I fix my sed command, to change the appropriate line for the hibernate config blocks?

edit: It seems like I cant get sed groups with newlines not to work at all.

Answer 1

Sed is line-based by default - to do multi-line matches you would need to add lines to the pattern space explicitly (using the N command for example).

Instead you could do something like this which is still line-based but steps forward to load the line of interest:

$ sed '/^\[Disable hibernate/{n;n;n;/^ResultActive/s/=no/=yes/;}' file.pkla
[Update already installed software]
Identity=unix-group:admin;unix-group:sudo
Action=org.debian.apt.upgrade-packages
ResultActive=yes

[Printer administration]
Identity=unix-group:lpadmin;unix-group:admin;unix-group:sudo
Action=org.opensuse.cupspkhelper.mechanism.*
ResultActive=yes

[Disable hibernate by default in upower]
Identity=unix-user:*
Action=org.freedesktop.upower.hibernate
ResultActive=yes

Note that like your original, this will only work if the order of lines in the block can be relied on.