variable in sed

Question

how can I use a variable as a pattern finder for sed? for example:

sed -i \'/$pc/ s/off/on/\' ~/Documents/Mantenimiento

I know there is a

Answer 1

Use double quotes instead of single quotes, or close the quotes just before the variable and reopen them just after.

sed -i "/$pc/ s/off/on/"
sed -i '/'$pc'/ s/off/on/'

This will let bash perform the variable evaluation normally.