Execute commands after logging in into the ssh connection not locally

Sayan Acharjee · 10-20-2010, 10:45 PM

Hi,

I am creating this script which will login to a server with ssh and check if a particular exists there, if not it will create the user.

This is the script:

Quote:

ssh 192.168.100.5

cat /etc/passwd|grep -i $1 > /dev/null
if [ $? -eq 0 ];
then
echo "User already exists";
else
{
useradd $1
echo $1|passwd --stdin $1 > /dev/null
}
fi

After running the script it is asking for ssh password, which is fine.
But the problem is, its not doing the rest of the work after logging in into the server, its checking and creating the user only when I'm logging out of the ssh connection, means the user is created locally only and not in the server.
How can I force this script to execute the rest of the commands in the server after logging in, not in the client?

Thanks in advance

archtoad6 · 10-21-2010, 07:06 AM

While this is not a trivial question -- I don't know the answer off the top of head -- I am surprised at a man w/ your credentials asking it.

Did you Google on it? If so, it would help us to not repeat your efforts if you would show us your search terms.

Did you re-read the man page? I believe your answer is there; although it took me a 2nd read to see it.

trey85stang · 10-23-2010, 08:55 PM

you're close, try putting the "script" you want to run on the remote server in quotes like so:

Code:

ssh 192.168.100.5 "if grep -iq $1 /etc/passwd
  then
    echo \"User already exists\"
  else
    useradd $1
    echo $1|passwd --stdin $1 > /dev/null 2>&1
  fi
"

I cleaned up your script a hair too since im anal... there is no reason to use cat with grep as grep is perfectly capable of reading from the file system. Also no reason to redirect with grep either if you dont want to see the output -q will supress printing out. Next, the if statement is good to check a command for return status, a 0 is true, anything else is false. Last "> /dev/null" only redirects stdout, just fyi.

edit: Inside the "'s you have to escape " and ', so the echo commadn would need to be llike so to work:

echo \"blah blah blah\" I do this all day every day and always forget that... not surprised i forgot to do it here.

Sayan Acharjee · 10-25-2010, 01:58 AM

Quote:

Originally Posted by trey85stang

you're close, try putting the "script" you want to run on the remote server in quotes like so:

Code:

ssh 192.168.100.5 "if grep -iq $1 /etc/passwd
  then
    echo \"User already exists\"
  else
    useradd $1
    echo $1|passwd --stdin $1 > /dev/null 2>&1
  fi
"

I cleaned up your script a hair too since im anal... there is no reason to use cat with grep as grep is perfectly capable of reading from the file system. Also no reason to redirect with grep either if you dont want to see the output -q will supress printing out. Next, the if statement is good to check a command for return status, a 0 is true, anything else is false. Last "> /dev/null" only redirects stdout, just fyi.

edit: Inside the "'s you have to escape " and ', so the echo commadn would need to be llike so to work:

echo \"blah blah blah\" I do this all day every day and always forget that... not surprised i forgot to do it here.

Hi trey85stang,

Its really working, thanks a lot.

This is the script I am using now

Quote:

ssh $2 "if [ $(id -g) -eq 0 ]
then
if grep -iq $1 /etc/passwd
then
echo "User already exists"
else
{
sudo /usr/sbin/useradd $1
echo $1|passwd --stdin $1 > /dev/null

}
fi

else
echo "Error: You ust be root"
fi
"

But here the sudo is not working, its throwing this error:

Quote:

sudo: sorry, you must have a tty to run sudo

Can you please tell me how to provide a tty to run sudo in the script?

Sayan Acharjee · 10-25-2010, 06:44 AM

EDIT:[content removed]

Sayan Acharjee · 10-25-2010, 09:15 AM

So, how to declare the tty for the ssh connection? any idea?

trey85stang · 10-25-2010, 10:19 AM

im not sure, i have never run into that problem. You should have a pseudo terminal assigned which should work fine for sudo

Sayan Acharjee · 10-27-2010, 02:01 AM

Quote:

Originally Posted by trey85stang

im not sure, i have never run into that problem. You should have a pseudo terminal assigned which should work fine for sudo

Hey thanks for the concern, yes I know the terminal should be declared in the script in order to do that and I have tried with $TTY_SSH=/dev/pts/1 and $TTY=/dev/pts/1 and found both of them are not working.

If anyone knows how to declared the terminal in the script kindly let me know.
Thanks in advance.

trey85stang · 10-28-2010, 01:06 PM

sayan, I just though of something.. perhaps the useradd command is requirng you to have an interactive terminal session. Doesnt useradd want you to enter in information? Im thinking it does and its not a sudo problem but a useradd problem.

Sayan Acharjee · 10-30-2010, 10:56 AM

Quote:

Originally Posted by trey85stang

sayan, I just though of something.. perhaps the useradd command is requirng you to have an interactive terminal session. Doesnt useradd want you to enter in information? Im thinking it does and its not a sudo problem but a useradd problem.

Thanks for bothering

I'm not sure about it, need to check again, will let you know the result.