Hi all

Please help i am new to unix environment.

i am getting error in this script,i am in same dir,and executing as ./login
error:command not found root

if [ "$LOGNAME" != "root" ]
then
LINES=`who | grep -c $LOGNAME`
if [ "$LINES" -gt "1" ]
then
echo "Already logged in!"
sleep 5
exec /bin/true
fi
fi

# Now it is working fine after removing quotes from $LOGNAME
but, i want to prevent multiple login in "root" user, how can i do that

Are you sure the punctuation is as you show it? ", ' and ` all have special meanings. As shown it should work but the message suggests it thinks you're trying to execute a command called root rather than check for value. Make sure your $LOGNAME and root actually have double quotes and not back ticks on them.

Also you might want to try removing the quotes from $LOGNAME since it is a variable.

What shell is this being run in?

thanks for reply

# Now it is working fine after removing quotes from $LOGNAME
but, i want to prevent multiple login in "root" user, how can i do that

What distro are you using? How is root logging in, via the console? This may be a bit more detailed that it appears, so as much info would really help.

Suggestion: Please put your code with code tags, it preserves formatting and makes it much easier to read.

#This is my code. using ssh and i am login through console


if [ "$LOGNAME" != "root" ]
then
LINES=`who | grep -c $LOGNAME`
if [ "$LINES" -gt "1" ]
then
echo "Already logged in!"
sleep 5
exec /bin/true
fi
fi

Please put code tags around your code:
Now what distro are you using, Debian, Fedora openSUSE etc?

Hi,

i did not get properly your query(Please put code tags around your code
how can i put it,and i am using putty.

You tag your stuff with "code" by highlighting it then clicking on the thing that looks like a pound/number sign (octothorpe) "#" above the text box. That puts HTML code tags around what you highlight. (Similarly clicking on the thing to the left of it will put HTML quote tags around what you highlight.

As to your other question - simply change your code to remove the first test:

Your first test is saying NOT to do the next test if the login IS root so by removing that test you'll also be testing for root.

If on the other hand you ONLY want to do this when it IS root and no other user you should modify it to remove the exclamation (which is negation in "test" - i.e. use "=" rather than "!=") from your first test:

Personally I would change
ie if doing an arithmetical comparison, you don't use string params.
Also, I prefer [[ ]] http://tldp.org/LDP/abs/html/testcon...ml#DBLBRACKETS as more robust.

1 members found this post helpful.

Good catch on the quotes - I hadn't noticed them.

Hi thanks,

Now code is working fine in below code: but it is not able to prevent multiple login yet
i have logged as a user, can i do at my level ?


if [ $LOGNAME = "root" ]
then
LINES=$(who | grep -c $LOGANAME)
if [[ "LINES" -gt "1" ]]
then
echo "multiple user logged"
sleep 5
exec /bin/true
exit 0
fi
fi

I don't understand your question. If you are a user other than root then your code has no meaning as it only checks to see if you are root.

Does it work when you are trying multiple root logins? Where did you put the code (i.e. is it in /etc/profile, root's .bashrc or what)?

Also why do you have:
Then an exit?

exec says to replace the current process (the shell) with the command (/bin/true). Since /bin/true simply sets a status and exits there is no need for the following exit. Your code would be simpler if it merely did the exit and not the exec /bin/true. Why are you waiting 5 seconds for the exit?

1. LOGNAME not same as LOGANAME

2. see my prev post about numeric comparisons