sed: unsupported command e

/in /by

If, when you try to use sed command to do a search and replace you get the following error:

sed: unsupported command e

Then you may have forgotten to include ‘s’ at the start of the command, e.g. this will produce the error:

sed  -i '/^server\s\+\S\+$/server 192.168.1.145/' test.conf

While this will work ok (note the all important ‘s’):

sed  -i 's/^server\s\+\S\+$/server 192.168.1.145/' test.conf

PS Happy New Year!