I have hard requirement of logging into a terminal via SSH from TCL console and relaunch a tcl script from that terminal. For this I use exec command and it does get executed. The only problem is it doesn't return back to parent code.
I have automated SSH login and it works fine from a bash/csh terminal
But from TCL console, the following happens
Simple example
exec ssh hostname pwd
puts "Done"
When I execute this code in TCL, "Done" never gets printed. I just get the output of pwd and that's it.
I have a need of looping SSH into multiple terminals and run TCL jobs on a hardware, but the loop gets stuck after executing the first SSH.
I search the internet for answers and I am not able to find any. Please help.
There could be a lot issues going on here. Running ssh with an explicit command (pwd) will usually default to not allocating a tty (ssh -T) and will run the remote shell in non-interactive mode. And the output of a command called from exec is not normally echoed to standard output, so I would not expect you to see the output if you call it from a script. You have to print the result of exec to see the output of the pwd command. Also, different shell startup scripts are run on the remote host depending on which shell the account is set up with and whether it is an interactive or non-interactive shell. It could be .bashrc, .bash_profile, .profile, .cshrc, etc., and if the script behaves differently when it has a tty vs. when it doesn't, that could explain differing behavior between a bash/csh shell and the TCL console.
Without having access to your system, it is hard for me to troubleshoot. I would start with a script like this:
set result [exec ssh -T hostname pwd]
puts "result = $result"
puts "Done."
Then I would try changing the -T to a -t and trying again. If the output of "pwd" is appearing before the "result =" line, then you can tell that the command is writing the result to a tty instead of standard output, and that's useful information for troubleshooting.
Related
When I am doing SSH to some machine inside the for loop it is doing the ssh but not able to execute further.
Code is like:
string=c01.test.cloud.com,c02.test.cloud.com
for i in $(echo $string | sed "s/,/ /g")
do
ssh -t -t AppAccount#$i
cd a/b/c
str2=x,y,z
done
I take it from your question that you expect cd a/b/c to run on a remote server? That's not what this script is doing. The call to ssh opens an SSH tunnel, and provides you an interactive terminal connection. It then waits for that connection to terminate. (I suspect if you pressed Control-D, the script would continue.) Your use of -t -t here is particularly strange. Why do you want to force a remote pty? This is making the problem worse (not that much, since it won't work anyway, but this seems the opposite of what you'd want).
I think this is the script you meant:
string=c01.test.cloud.com,c02.test.cloud.com
for i in $(echo $string | sed "s/,/ /g")
do
ssh AppAccount#$i 'cd a/b/c; str2=x,y,z'
done
(This won't do anything of course, but I assume your real script has more to it than setting a shell variable and exiting.) The point is that you ned to pass the script you want to run as a parameter to ssh. Otherwise it's going to spawn an interactive shell and wait for you to close it.
Note that if your script is very complicated, it can be very inconvenient to stick it all in a single-quoted string. If your internal script is in its own file, a simple way to handle this is with bash -s which reads a script from stdin:
cat some_script | ssh server 'bash -s'
You can also use bash Here docs to achieve the same thing, but that is likely getting too fancy for this use.
I want to run a few shell commands every time I SSH to a server via PuTTY. I'm connecting to a production web server managed by someone else, and I don't want to store my own scripts there.
I see the option Connection > SSH > Remote Command, but if I put my initialization commands there, after starting the session, it closes immediately after the commands execute. How can I run the Remote Command, and then keep the session open so I can continue using it?
The SSH session closes (and PuTTY with it) as soon as the command finishes. By default the "command" is a shell. As you have overridden this default "command" and yet you want to run the shell nevertheless, you have to explicitly execute the shell yourself:
my-command ; /bin/bash
See also Executing a specific command on the server.
One option to go is set up your putty remote command like this:
ls > dir.ls & /bin/bash
In this example command you want to run is "ls > dir.ls" what creates file dir.ls with content of directory listing.
And as you want to leave shell open you can add aditional command "/bin/bash" or any other shell of your choice.
I want to run a script remotely. But the system doesn't recognize the path. It complains that "no such file or directory". Am I using it right?
ssh kev#server1 `./test/foo.sh`
You can do:
ssh user#host 'bash -s' < /path/script.sh
Backticks will run the command on the local shell and put the results on the command line. What you're saying is 'execute ./test/foo.sh and then pass the output as if I'd typed it on the commandline here'.
Try the following command, and make sure that thats the path from your home directory on the remote computer to your script.
ssh kev#server1 './test/foo.sh'
Also, the script has to be on the remote computer. What this does is essentially log you into the remote computer with the listed command as your shell. You can't run a local script on a remote computer like this (unless theres some fun trick I don't know).
If you want to execute a local script remotely without saving that script remotely you can do it like this:
cat local_script.sh | ssh user#remotehost 'bash -'
It works like a charm for me.
I do that even from Windows to Linux given that you have MSYS installed on your Windows computer.
I don't know if it's possible to run it just like that.
I usually first copy it with scp and then log in to run it.
scp foo.sh user#host:~
ssh user#host
./foo.sh
I was able to invoke a shell script using this command:
ssh ${serverhost} "./sh/checkScript.ksh"
Of course, checkScript.ksh must exist in the $HOME/sh directory.
Make the script executable by the user "Kev" and then remove the try it running through the command
sh kev#server1 /test/foo.sh
i want to run some command on several machine using ssh. I know it can be done by just using the command "ssh user#hostname command". However, the command i want to run print some string on the console. Is there any way that send all the strings back to the console that i'm on?
You could run the commands in a screen:
screen -S test
ssh user#hostname command1
ssh user#hostname2 command2
You can then detach (Ctrl-D) from the screen, let it run for however long it will run, then re-attach (screen -r test) to the screen and see all of the output. This assumes that you won't have a ton of output from the commands, however. Here's a link to a tutorial on screen.
ssh user#hostname command
Does just that. if 'command' outputs something, it'll show on the terminal you ran ssh from.
Try e.g. ssh user#hostname ls -l
But as others have said, GNU screen is invaluable for this type of work.
You probably want to use Gnu Screen for this. You can start a process in a "virtual" terminal, "detach" the terminal and log out for however long you want... Then you can ssh back in and re-attach the terminal to see the console output.
Also have a look at nohup, for example:
ssh user#domain.com nohup script_that_outputs_strings.py > the_strings.txt
Then if you want to go back and monitor the progress, you could check back and tail the file or scp the output back to your local machine.
Why don't you send you an email back?
Or use a log file, and scp it to your current computer?
otherwise, I don't know!
How do I execute a command every time after ssh'ing from one machine to another?
e.g
ssh mymachine
stty erase ^H
I'd rather just have "stty erase ^H" execute every time after my ssh connection completes.
This command can't simply go into my .zshrc file. i.e. for local sessions, I can't run the command (it screws up my keybindings). But I need it run for my remote sessions.
Put the commands in ~/.ssh/rc
You can put something like this into your shell's startup file:
if [ -n "$SSH_CONNECTION" ]
then
stty erase ^H
end
The -n test will determine if SSH_CONNECTION is set which happens only when logged in via SSH.
If you're logging into a *nix box with a shell, why not put it in your shell startup?
.bashrc or .profile in most cases.
Assuming a linux target, put it in your .profile
Try adding the command below the end of your ~/.bashrc. It should be exited upon logoff. Do you want this command only executed when logging off a ssh session? What about local sessions, etc?
trap 'stty erase ^H; exit 0' 0
You probably could setup a .logout file from /etc/profile using this same pattern as well.
An answer for us, screen/byobu users:
The geocar's solution will not work as screen will complain that "Must be connected to a terminal.". (This is probably caused by the fact that .ssh/rc is processed before shell is started. See LOGIN PROCESS section from man 8 sshd).
Robert's solution is better here but since screen and byobu open it's own bash instance, we need to avoid infinite recursion. So here is adjusted byobu-friendly version:
## RUN BYOBU IF SSH'D ##
## '''''''''''''''''' ##
# (but only if this is a login shell)
if shopt -q login_shell
then
if [ -n "$SSH_CONNECTION" ]
then
byobu
exit
fi
fi
Note that I also added exit after byobu, since IMO if you use byobu in the first place, you normally don't want to do anything outside of it.