Removing line from executing script
 

Developing a script which leaves data in the script which runs the command to remove and write a line.
Done this to scripts b4 but am drawing a blank on removal and get an error.
Shell returns error: sed: -e expression #1, char 4: extra characters after command
Couldn't find any examples with my search query so needing help.
BTW have use echo statements to validate variables and output.

You are using single quotes instead of double quotes which prevent the shell from expanding the variable:

Regrets for not listing the entire script correctly here is with echo statements:
Yes this works but the entire script is lost. Need to keep script with the ##data statement removed as will write a new ##data statement into the script's tail, i.e. keeping ##data info with the program that updates it.

The stdout redirection will result in $0 being opened as a new file before the command is executed. By the time 'sed' gets executed and accesses the file, it is empty.

Elaborating on saulgoode's answer (which is correct):

If you use a modern sed version (4+) you can use the -i flag to edit the file in-place:If you're using an older sed version:

that can be solved with a single sed:
sed -i '/^##data/d' <filename>
if I understand it well

druuna & pan64 U have it right! Thanks