Question

Suppose my file a.conf is as following

Include /1
Include /2
Include /3

I want to replace “Include /2” with a new line, I write the code in .sh file :

line="Include /2"
rep=""
sed -e "s/${line}/${rep}/g" /root/new_scripts/a.conf

But after running the sh file, It give me the following error

sed: -e expression #1, char 14: unknown option to `s' 

Answer 1

If you are using a newer version of sed you can use -i to read from and write to the same file. Using -i you can specify a file extension so a backup will be made, incase something went wrong. Also you don’t need to use the -e flag unless you are using multiple commands

sed -i.bak "s/${line}/${rep}/g" /root/new_scripts/a.conf

I have just noticed that as the variables you are using are quoted strings you may want to use single quotes around your sed expression. Also your string contains a forward slash, to avoid any errors you can use a different delimiter in your sed command (the delimiter doesn’t need to be a slash):

sed -i.bak 's|${line}|${rep}|g' /root/new_scripts/a.conf