[SOLVED] How to commet out specific lines of text?

justmy2cents · 07-25-2017, 03:15 PM

Hello ladies and gents, im trying to commet out tty2-tty63 in /etc/securetty (to disable unneeded terminals for security reasons). But everything that I have previously tried has failed to work.. Any ideas would be much appreciated, thank you! Btw this is what I already tried.

Code:

for i in `cat /etc/securetty|grep tty[2-63]` {1..63}; do
echo "#" >> $i
done

And im sure that's written completely wrong.

astrogeek · 07-25-2017, 04:50 PM

Not even in the ballpark!

Do you have to do it with a script? I think I would open an editor and search, replace those line and be done in 3 seconds.

If you need a scripted solution, sed would be the tool, maybe something like this...

Code:

sed -r 's/^tty([2-9]|1[0-9])/#&/' /etc/securetty

justmy2cents · 07-25-2017, 05:03 PM

Lol I tried.. Anywho thanks, and yeah it's going to be part of a script that does other configuration changes that I don't really want to do by hand, partly cause im a slow typer.

syg00 · 07-25-2017, 06:53 PM

I think a little differently - specify what you want to keep (one line) and comment everything else rather than have to construct potentially ever more complex regex.

Code:

 sed -r '/^tty1$/! s/^/#/' /etc/securetty

If you need to accommodate whitespace before the end of record, trivial to add.

MadeInGermany · 07-26-2017, 12:22 AM

This should be pretty safe

Code:

file=/etc/securetty
if [ -f $file ]; then
  cp -p $file $file.orig &&
  sed '/^tty1$/!s/^tty[1-9][0-9]*/#&/' $file.orig >$file
fi

It leaves a .orig file behind.

justmy2cents · 07-26-2017, 10:16 AM

Quote:

Originally Posted by astrogeek

Not even in the ballpark!

Do you have to do it with a script? I think I would open an editor and search, replace those line and be done in 3 seconds.

If you need a scripted solution, sed would be the tool, maybe something like this...

Code:

sed -r 's/^tty([2-9]|1[0-9])/#&/' /etc/securetty

Thanks worked like a charm.

justmy2cents · 07-26-2017, 10:18 AM

Quote:

Originally Posted by syg00

I think a little differently - specify what you want to keep (one line) and comment everything else rather than have to construct potentially ever more complex regex.

Code:

 sed -r '/^tty1$/! s/^/#/' /etc/securetty

If you need to accommodate whitespace before the end of record, trivial to add.

I think both modes of thinking are useful, so thanks that helps too!

justmy2cents · 07-26-2017, 10:20 AM

Quote:

Originally Posted by MadeInGermany

This should be pretty safe

Code:

file=/etc/securetty
if [ -f $file ]; then
  cp -p $file $file.orig &&
  sed '/^tty1$/!s/^tty[1-9][0-9]*/#&/' $file.orig >$file
fi

It leaves a .orig file behind.

I keep this one in mind if I need to do this in a work environment or something, but im just doing it in a live install so I not too worried about messing up the file.. Thanks bro!