I want to write a script that connects via ssh (ssh user#host) and runs watch who there.
Normally I would just do
ssh user#host
# I am now on the other machine
watch who
But a spript would wait until the first command is done and would start the second one. So my next try is
ssh user#host watch who
but I get an error ($? is 1) and a message:
"Error opening terminal: unknown"
ssh user#host who works just fine though. So how could I approach this?
(My real application is not to watching the users but watching the print queue, but the problem seems to be the same and I guessed that more people are familiear with who then with lpstat)
The watch needs a PTY, which is not allocated when you add a command to ssh. Use
ssh -t user#host "watch who"
Related
I' m sure you will find the question similar to many other posts on stackoverflow or on internet. However, I could not find the solution to my problem precisely. I have list of task to be run on remote server, and passing the script is OK! however does not suit to the requirement.
I' m running following from my server to connect to remote server;
ssh -t user#server << 'HERE'
sudo su - <diff_user>
do task as diff_user
HERE
ssh -tt user#server << 'HERE'
sudo su - <diff_user>
do task as diff_user
HERE
With first option (-t), I' m still not able to do sudo, it says below;
sudo: sorry, you must have a tty to run sudo
With second option above (-tt), I' m getting reverse input/output to current server session, total mess.
I tried passing the content as an script to SSH to run on remote host, however, getting similar results.
Is there a way other than commenting out below?
Defaults requiretty in /etc/sudoers file
I have not tried above though, I know RedHat approved it to be removed/ commented out in future version, whenever that is. If I go with step, I will have get above done in 100's of VM's (moreover, I dont have permission to edit the file on VM's and give it a try).
Bug 1020147
Hence, my issue remains the same, as before. It would be great if I can get some input from experts here :)
Addition Info : Using RedHat RHEL 6, 2.6.32-573.3.1
I do have access to the remote host and once I' m in, my ID does not require password to switch to diff_user.
When you are asking this way, I guess you don't have passwordless sudo.
You can't communicate with the remote process (sudo), when you put the script on stdin.
You should rather use the ssh and su command:
ssh -t user#server "sudo su - <diff_user> -c do task as diff_user"
but it might not work. Interactive session can be initiated using expect (a lot of questions around here).
I was trying to connect to another machine in an automated fashion and check some logs only accessible to root/sudo.
This was done by passing the password, server, user, etc. in a file — I know this is not safe and neither a good practice, but this is the way it will be done in my company.
I have several problems:
tcgetattr: Inappropriate ioctl for device;
tty related problems that I don't remember exactly;
sudo: sorry, you must have a tty to run sudo, etc..
Here is the code that worked for me:
#!/bin/bash
function checkLog(){
FILE=$1
readarray -t LINES < "$FILE"
machine=${LINES[4]}
user=${LINES[5]}
password=${LINES[6]}
fileName=${LINES[7]}
numberOfLines=${LINES[8]}
IFS='' read -r -d '' SSH_COMMAND <<EOT
sudo -S <<< '$password' tail $fileName -n $numberOfLines
EOT
RESULTS=$(sshpass -p $password ssh -tt $user#$machine "${SSH_COMMAND}")
echo "$RESULTS"
}
checkLog $1
I have a strange SSH problem.
If I run this
ssh user#remote 'md5sum file.txt'
I get back the result as expected, but if I run this
ssh user#remote 'cat file.txt'
then it just sits there.
I'll attribute this problems to bad network connection. I've started using Mosh and is works magnitudes better than ssh.
I am trying to connect to a remote host from my local host through the below command.But there was a setting in the remote host that soon after we login it will prompt to enter a badge ID,password and reason for logging in, because it was coded like that in profile file on remote-host How can I overcome those steps and login directly non-interactively, without disturbing the code in profile.
jsmith#local-host$ ssh -t -t generic_userID#remote-host
Enter your badgeID, < exit > to abort:
Enter your password for <badgeID> :
Enter a one line justification for your interactive login to generic_userID
Small amendment: to overcome remote server expect approach is required, but in case local script connects to bunch of remote servers, which configuration may be broken, just use SSH options:
ssh -f -q -o BatchMode=yes -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null USER#TARGETSYSTEM
This will omit ask for password in case there is no ssh_key setup, exit silently and continue with script/other hosts.
Puts ssh to background with -f, which is required when calling ssh command from sh (batch) file to remove local console redirect to remote input (implies -n).
Look into setting up a wrapper script around expect. This should do exactly what you're looking for.
Here are a few examples you can work from.
I have upvoted Marvin Pinto's answer because there is every reason to script this, in case there are other features in the profile that you need, such as Message of the Day motd.
However, there is a quick and dirty alternative if you don't want to make a script and you don't want other features from the profile. Depending on your preferred shell on the remote host, you can insist that the shell bypasses the profile files. For example, if bash is available on the remote host, you can invoke it with:
ssh -t -t generic_userID#remote-host bash --noprofile
I tested the above on the macOS 10.13 version of OpenSSH. Normally the command at the end of the ssh invocation is run non-interactively, but the -t flag allows bash to start an interactive shell.
Details are in the Start-up files section of the Bash Reference Manual.
The first thing I do after vagrant ssh is usually attaching to a tmux session.
I want to automate this, so I try: vagrant ssh -c "tmux attach", but it fails and says "not a terminal".
After some googling I find this article and know that I should force a pseudo-tty allocation before executing a screen-based program, and it can be done with the -t option of ssh.
But I don't know how to use this option with vagrant ssh.
According to this documentation, you should try adding -- to the command.
As I have not used vagrant, I am unsure of the formatting, but assume it would be similar to:
vagrant ssh -- -t
Unless, you need to include the username and host, in which case add the username and host.
I wish to use SSH to establish a temporary port forward, run a local command and then quit, closing the ssh connection.
The command has to be run locally, not on the remote site.
For example consider a server in a DMZ and you need to allow an application from your machine to connect to port 8080, but you have only SSH access.
How can this be done?
Assuming you're using OpenSSH from the command line....
SSH can open a connection that will sustain the tunnel and remain active for as long as possible:
ssh -fNT -Llocalport:remotehost:remoteport targetserver
You can alternately have SSH launch something on the server that runs for some period of time. The tunnel will be open for that time. The SSH connection should remain after the remote command exits for as long as the tunnel is still in use. If you'll only use the tunnel once, then specify a short "sleep" to let the tunnel expire after use.
ssh -f -Llocalport:remotehost:remoteport targetserver sleep 10
If you want to be able to kill the tunnel from a script running on the local side, then I recommend you background it in your shell, then record the pid to kill later. Assuming you're using an operating system that includes Bourne shell....
#/bin/sh
ssh -f -Llocalport:remotehost:remoteport targetserver sleep 300 &
sshpid=$!
# Do your stuff within 300 seconds
kill $sshpid
If backgrounding your ssh using the shell is not to your liking, you can also use advanced ssh features to control a backgrounded process. As described here, the SSH features ControlMaster and ControlPath are how you make this work. For example, add the following to your ~/.ssh/config:
host targetserver
ControlMaster auto
ControlPath ~/.ssh/cm_sockets/%r#%h:%p
Now, your first connection to targetserver will set up a control, so that you can do things like this:
$ ssh -fNT -Llocalport:remoteserver:remoteport targetserver
$ ssh -O check targetserver
Master running (pid=23450)
$ <do your stuff>
$ ssh -O exit targetserver
Exit request sent.
$ ssh -O check targetserver
Control socket connect(/home/sorin/.ssh/cm_socket/sorin#192.0.2.3:22): No such file or directory
Obviously, these commands can be wrapped into your shell script as well.
You could use a script similar to this (untested):
#!/bin/bash
coproc ssh -L 8080:localhost:8080 user#server
./run-local-command
echo exit >&${COPROC[1]}
wait