How can I use a file in a command and redirect output to the same file without truncating it?

Question

Basically I want to take as input text from a file, remove a line from that file, and send the output back to the same file. Something along these lines if that makes it any

Answer 1

Use sed instead:

sed -i '/seg[0-9]\{1,\}\.[0-9]\{1\}/d' file_name