Bash, remove lines containing string with grep

Question

This is currently deleting the whole contents of the file in question:

#!/bin/bash
rpc_port="9201";
dir="/etc/apache2/ports.conf"
cat $dir | grep -v "Listen $rpc_port" > $dir

The file contents:

Listen 9200
Listen 9201
Listen 9202
Listen 9203
Listen 9204

Could someone please either fix this or give me a working alternative? :)

Answer 1

You cannot write (=redirect) to the same file you are reading from. Either redirect to a different file, or use sed.

sed -i "/$rpc_port/d" $dir