' in sed appearing in the wrong place

I am trying to set an IP in a file with sed. I am running this command

sed -i 's:$dbserver='':$dbserver='10.0.0.2':' t.conf

but when I look in t.conf the line is

$dbserver=10.0.0.2''

Anyone know why the two single quotes are appearing at the end of the line?

I am runn开发者_如何学JAVAing Debian Linux

You need to enclose the second sed argument in double quotes:

sed -i "s:$dbserver='':$dbserver='10.0.0.2':" t.conf

This way $dbserver will be substituted with its value before being passed to sed, and the single quotes won't need escaping.

If you want $dbserver to appear literally in the conf file, preceed the dollar signs with a backslash.