sed permission denied when overwriting file

Question

I am trying to use sed to overwrite my index.php file, but I am getting an error:

$ sed -i \'s@@

        

Answer 1

If the use of sed is not a hard requirement, you can probably use the highly ignored command ed.

ed -s index.php <<< $'%s@@@\nwq'

• The <<< '' construct will pipe '' into the as standard input
• The $'...' construct will be parsed for special characters. In this case the \n splits the string into two lines
• You can use any construct you want to generate and pipe in the input (echo, printf, etc.)

Standard Input String:

%s@@@
wq

The first line is your regex search and replace as command for ed. The second line tells ed to write the changes and quit. You may recognize these commands from vi.

source: mrbluecoat.blogspot.com/2014/03/in-place-editing-right-way-hint-dont.html