I have the following command that correctly creates the /etc/hosts file that I want to build. However, I cannot write it per the 2nd form due to permissions, of course. So I tried variations of the 3rd form, but it still errors on permissions. Can someone give me a suggestion to try?

cat hosts.tmp ; echo -n "myremotehost " ; cat ip.txt

cat hosts.tmp ; echo -n "myremotehost " ; cat ip.txt > /etc/hosts

cat hosts.tmp ; echo -n "myremotehost " ; echo mypassword | sudo -S cat ip.txt > /etc/hosts
  • I suspect you might be trying to re-invent the wheel here: gaenserich.github.io/hostsblock -- anyway, if that's not the case, you can perhaps get answers to your question(s) in the script(s) there ;-) – Sadi Sep 26 '13 at 12:43

This was hard for me to find out! (Relative newbie to Linux.)

In terminal, type sudo -i, then log in with your user password. You will be in the root directory, with God-like powers... :>)

I also found bash filename.sh will start the script. Forgive me, I feel a great sense of accomplishment having written a script (per suggestions in another post) which killed all ads in Youtube!


I would put the instructions to modify your /etc/hosts file in a shell script, say modify-hosts.sh, then execute

sudo modify-hosts.sh

If you insist on running the script without having to provide a password, then add a NOPASSWD entry specifically for this script and your username to /etc/sudoers.

As for the contents of the file, you could do:

cp hosts.tmp > /etc/hosts
echo "myremotehost $(cat /path/to/ip.txt)" >> /etc/hosts

More conveniently, if myhostname already has an entry in /etc/hosts you can edit it in place:

sed -i -e 's/myhostname .*/myhostname '$(cat ip.txt)'/' /etc/hosts

And that statement you can even sudo on one line

sudo sed -i -e 's/myhostname .*/myhostname '$(cat ip.txt)'/' /etc/hosts

without running into redirection issues.

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