I've got the "bash-completion" package installed.
ssh completion on the command line (in bash) is working: ssh TAB-TAB will complete past used hosts and ssh -TAB-TAB will complete available ssh options.
However when I search for currently defined completions:
$ complete | grep ssh
complete -F _known_hosts ssh-installkeys
complete -F _service /etc/init.d/ssh
... I find that there's no completion registered for ssh ?!
complete -p ssh
bash: complete: ssh: no completion specification
When I check the ssh completions script under /usr/share/bash-completion/completions/ssh then I see that indeed it does register ssh completions:
$ grep complete /usr/share/bash-completion/completions/ssh | grep ssh | grep -v '^#'
shopt -u hostcomplete && complete -F _ssh ssh slogin autossh sidedoor
So why doesn't the ssh completion show up in complete | grep ssh? How does bash complete the ssh options?
If there is no completion defined for a command (or a function or whatever) then the "default" completer kicks in.
That default completer can be seen here:
$ complete -p -D
complete -F _completion_loader -D
When the bash-completion package is installed, then that will source /usr/share/bash-completion/bash_completion via /etc/bash.bashrc and that will assign the _completion_loader function.
_completion_loader will dynamically load specific completers upon completion request for commands the shell's completer doesn't know about yet (see here).
In the case of ssh, the terminals where I was doing the poking around had not yet loaded the ssh completer and so I was not seeing it with complete | grep ssh or complete -p ssh. It's only at the moment when you press TAB-TAB for the first time that the completer for ssh gets loaded.
Related
I'm getting incredibly frustrated here. I simply want to run a sudo command on a remote SSH connection and perform operations on the results I get locally in my script. I've looked around for close to an hour now and not seen anything related to that issue.
When I do:
#!/usr/bin/env bash
OUT=$(ssh username#host "command" 2>&1 )
echo $OUT
Then, I get the expected output in OUT.
Now, when I try to do a sudo command:
#!/usr/bin/env bash
OUT=$(ssh username#host "sudo command" 2>&1 )
echo $OUT
I get "sudo: no tty present and no askpass program specified". Fair enough, I'll use ssh -t.
#!/usr/bin/env bash
OUT=$(ssh -t username#host "sudo command" 2>&1 )
echo $OUT
Then, nothing happens. It hangs, never asking for the sudo password in my terminal. Note that this happens whether I send a sudo command or not, the ssh -t hangs, period.
Alright, let's forget the variable for now and just issue the ssh -t command.
#!/usr/bin/env bash
ssh -t username#host "sudo command" 2>&1
Then, well, it works no problem.
So the issue is that ssh -t inside a variable just doesn't do anything, but I can't figure out why or how to make it work for the life of me. Anyone with a suggestion?
If your script is rather concise, you could consider this:
#!/usr/bin/env bash
ssh -t username#host "sudo command" 2>&1 \
| ( \
read output
# do something with $output, e.g.
echo "$output"
)
For more information, consider this: https://stackoverflow.com/a/15170225/10470287
I would like to know what is the difference between the below commands:
ssh vagrant#someipaddress
cd /home/vagrant/
grep -i "something" data.txt
and
ssh vagrant#someipaddress 'cd /home/vagrant; cat data.txt' | grep -i "something"
From this website it mentions, that you can send multiple commands to the remote server. Is the second option actually logging into the server? What is the benefit in this second approach?
Strictly Speaking from the example provided:
The first command:
Logs onto the remote server
Executes a couple commands, and
Stays logged on to the server
The second command runs half on the remote machine, logs out of the remote machine, and then pipes the output to grep on your local machine, all in one command line.
Breaking down what's happening:
ssh vagrant#someipaddress 'cd /home/vagrant; cat data.txt' | grep -i "something"
The section in bold is running on your local PC, based on the output from the ssh session
The 'quotes "contain" the entire command block
the " quotes "contain" the individual arguments within the command block.
You may have meant to do this:
ssh vagrant#someipaddress 'cd /home/vagrant; cat data.txt' | grep -i "something"
Where the bold section runs locally
Or you may have intentionally done this:
ssh vagrant#someipaddress 'cd /home/vagrant/ | grep -i "something" data.txt'
Where the entire command runs on the server.
Either way, the end result:
Is that you automatically log out of the remote machine, and the whole command sequence was executed in one hit.
I am trying to run a nested ssh -t -t but it won't provide me the environment variables when working with cat and echo.
#!/bin/bash
pass="password\n"
bla="cat <(echo -e '$pass') - | sudo -S su -"
ssh -t -t -t -t jumpserver "ssh -t -t -t -t server \"$bla\" "
I get an output without any variables taken into consideration. (e.g. PS1 does not get shown but commands work fine) The problem is related to cat <(echo -e '$pass') - but this was the way to keep echo alive after providing the password for sudo.
How can i achieve this and get environment variables to get a proper output?
Thanks.
The -tt is enough. Using more -t does not add any more effect and just makes an impression that you have no idea what are you doing.
What is the point of cat <(echo -e) construction? Writing just echo would result in the same, isn't it?
Why to use sudo su? sudo already does all you need, isn't it?
So how can it look in some fashionable manner?
pass="password\n"
bla="echo '$pass' | sudo -Si"
ssh -tt jumpserver "ssh -tt server \"$bla\""
And does it work? Try to debug the commands with -vvv switches to the ssh. It will show you what is actually executed and passed to each other shell.
I'd like to capture the output of an ssh session. However, I first need to ssh twice (from my local computer to the remote portal to the remote server), then run a command and capture the output.
Doing this line-by-line, I would do:
ssh name#remote.portal.com
ssh remote.server.com
remote.command.sh
I have tried the following:
server=remote.server.com ##define in the script, since it varies
sshoutput=$(ssh -tt name#remote.portal.com exec "ssh -tt ${server} echo \"test\"")
echo $sshoutput
I would expect the above script to echo "test" after the final command. However, the outer ssh prompt just hangs after I enter my command and, once I Ctrl+c or fail to enter my password, the inner ssh session fails (I believe since stdout is no longer printed to screen and I no longer get my password prompt).
If I run just the inner command (i.e., without "sshoutput=$(" to save it as a variable), then it works but (obviously) does not capture output. I have also tried without the "exec".
I have also tried saving the inner ssh as a variable like
sshoutput=$(ssh -tt name#portal myvar=$(ssh -tt ${server} echo \"test\"") && echo $myvar)
but that fails because BASH tries to execute the inner ssh before sending it to the outer ssh session (I believe), and the server name is not recognized.
(I have looked at https://unix.stackexchange.com/questions/89428/ssh-twice-in-bash-alias-function but they simply say "more flags required if using interactive passwords" and do not address capturing output)
Thanks in advance for any assistance!
The best-practice approach here is to have ssh itself do the work of jumping through your bouncehost.
result=$(ssh \
-o 'ProxyCommand=ssh name#remote.portal.com nc -w 120 %h %p' \
name#remote.server.com \
"remote.command.sh")
You can automate that in your ~/.ssh/config, like so:
Host remote.server.com
ProxyCommand ssh name#remote.portal.com nc -w 120 %h %p
...after which any ssh remote.server.com command will automatically jump through remote.portal.com. (Change nc to netcat or similar, as appropriate for tools that are installed on the bouncehost).
That said, if you really want to do it yourself, you can:
printf -v inner_cmd '%q ' "remote.command.sh"
printf -v outer_cmd '%q ' ssh name#remote.server.com "$inner_cmd"
ssh name#remote.portal.com bash -s <<EOF
$outer_cmd
EOF
...the last piece of which can be run in a command substitution like so:
result=$(ssh name#remote.portal.com bash -s <<EOF
$outer_cmd
EOF
)
I'm writting a shell script and I want to automate login into a remote machine using ssh-copy-id, so manually when I print :
ssh-copy-id -i /root/.ssh/id_rsa $2#$4 -p $3 | echo $1
$1 refer to password,
$2 refer to username,
$3 refer to port, and
$4 refer to ip,
It is ok with that, the problem is that I have to automate inserting password after :
ssh-copy-id -i /root/.ssh/id_rsa $2#$4 -p $3
I add this "| printf $1", but it does not work it shows "password:" in the screen and still wait for the password ..
I hope you understand me and thank you.
As #Leon pointed out, you had the pipeline backwards. But even if you do it with the correct order, it will still not work because ssh-copy-id (and all other programs from openssh) do not read passwords from their stdin. The solution is to use the $SSH_ASKPASS environment variable. You can do that as follows: first, create an auxiliary script, say /var/tmp/ssh-pass.sh (actually find a better name than that), with the following contents:
#!/bin/sh
echo "$PASS"
Then you can use the following command to accomplish what you've asked for:
PASS="$1" SSH_ASKPASS="/var/tmp/ssh-pass.sh" setsid -w ssh-copy-id -i /root/.ssh/id_rsa "$2"#"$4" -p "$3"
Explanation: we use setsid -w to disassociate the ssh-copy-id process from the currently used terminal. That forces ssh-copy-id to run the executable specified in the $SSH_ASKPASS in order to obtain the password. We have specified our own script in that variable, so ssh-copy-id will execute just that. Now the script is supposed to provide the password to ssh-copy-id by printing it to its stdout. We use the $PASS variable to the password to the script, so the script just prints that variable.
2020 / Mac OS X:
Install sshpass (original answer)
brew install hudochenkov/sshpass/sshpass
Run ssh-copy-id using sshpass and with the password as an arg
sshpass -p $1 ssh-copy-id -i ~/PATH/TO/KEY $2#$4 -p $3
If you want to turn off strict host checking as well, use the -o flag, which is passed to the underlying ssh:
sshpass -p hunter2 ssh-copy-id -o StrictHostKeyChecking=no -i ~/PATH/TO/KEY $2#$4 -p $3
I tried the solution by #redneb, and installed setsid through util-linux by following this answer, but kept receiving a password denied.
I found this strategy to work for uploading my SSH key while setting up multiple raspberry pis in successino. In my script, I also run ssh-keygen -R raspberrypi.local each time too, to avoid the The ECDSA host key for raspberrypi.local has changed error.