I have multiple repos on my remote server like this:
sourcecode/
repoA
repoB
repoC
Each time I have to work on the remote machine on a repo (say repoA), I do two things:
ssh to remote-server
cd sourcecode/repoA on remote
Instead of doing this all the time, I would like to be able to have an alias / function on my Mac such that when I do "ssh-with-fancy-function" and pass argument: repoA , it should ssh into the remote server and after that is complete, should change my current directory on the remote server to sourcecode/repoA and stay.
How can I do this ?
ssh_cd() {
if (( $# != 1 )); then
echo "usage: ${FUNCNAME[0]} remote_dir" >&2
return 1
fi
printf -v cmd 'cd %q && bash -i' "$1"
ssh -t user#remote-host "$cmd"
}
The key here is that you end the command with bash -i to start an interactive shell; and the -t ssh option to ensure you have a tty to interact with.
This assumes your remote shell is bash.
So i am running this script to check if a java server is up remotely by sshing into remote. If it is down, i am trying to exit and run another script locally. However, after the exit command, it is still in the remote directory.
ssh -i ec2-user#$DNS << EOF
if ! lsof -i | grep -q java ; then
echo "java server stopped running"
# want to exit ssh
exit
# after here when i check it is still in ssh
# I want to run another script locally in the same directory as the current script
./other_script.sh
else
echo "java server up"
fi;
EOF
The exit is exiting the ssh session and so never gets to the execution of the other_script.sh line in the HEREDOC. It would be better to place this outside of the script and actioned from the exit status of the HEREDOC/ssh and so:
ssh -i ec2-user#$DNS << EOF
if ! lsof -i | grep -q java ; then
echo "java server stopped running"
exit 7 # Set the exit status to a number that isn't standard in case ssh fails
else
echo "java server up"
fi;
EOF
if [[ $? -eq 7 ]]
then
./other_script.sh
fi
I have a remote bash script, which goes through files using a for loop:
#!/bin/bash
for f in *.pdf;
do
echo $f
done
When executed locally:
server$./test.sh
1508.01585.pdf
1605.07683.pdf
When executed through ssh from a remote client:
client$ ssh user#server 'bash -c ~/papers/test.sh'
*.pdf
I have tried using ssh -T, bash -s, and nothing seems to work.
Please help!
Hi what is the best way to check to see if SSH fails for whatever reason?
Can I use a IF statement ( if it fails then do something)
I'm using the ssh command in a loop and passing my hosts names form a flat file.
so I do something like:
for i in `cat /tmp/hosts` ; do ssh $i 'hostname;sudo ethtool eth1'; done
I get sometime this error or I just cannot connect
ssh: host1 Temporary failure in name resolution
I want to skip the hosts that I cannot connect to is SSH fails. What is the best way to do this? Is there a runtime error I can trap to bypass the hosts that I cannot ssh into for whatever reason, perhaps ssh is not allowed or I do not have the right password ?
Thanking you in advance
Cheers
To check if there was a problem connecting and/or running the remote command:
if ! ssh host command
then
echo "SSH connection or remote command failed"
fi
To check if there was a problem connecting, regardless of success of the remote command (unless it happens to return status 255, which is rare):
if ssh host command; [ $? -eq 255 ]
then
echo "SSH connection failed"
fi
Applied to your example, this would be:
for i in `cat /tmp/hosts` ;
do
if ! ssh $i 'hostname;sudo ethtool eth1';
then
echo "Connection or remote command on $i failed";
fi
done
You can check the return value that ssh gives you as originally shown here:
How to create a bash script to check the SSH connection?
$ ssh -q user#downhost exit
$ echo $?
255
$ ssh -q user#uphost exit
$ echo $?
0
EDIT - I cheated and used nc
Something like this:
#!/bin/bash
ssh_port_is_open() { nc -z ${1:?hostname} 22 > /dev/null; }
for host in `cat /tmp/hosts` ; do
if ssh_port_is_open $host; then
ssh -o "BatchMode=yes" $i 'hostname; sudo ethtool eth1';
else
echo " $i Down"
fi
done
On Cygwin, I want a Bash script to:
Create an SSH tunnel to a remote server.
Do some work locally that uses the tunnel.
Then shut down the tunnel.
The shutdown part has me perplexed.
Currently, I have a lame solution. In one shell I run the following to create a tunnel:
# Create the tunnel - this works! It runs forever, until the shell is quit.
ssh -nNT -L 50000:localhost:3306 jm#sampledomain.com
Then, in another shell window, I do my work:
# Do some MySQL stuff over local port 50000 (which goes to remote port 3306)
Finally, when I am done, I close the first shell window to kill the tunnel.
I'd like to do this all in one script like:
# Create tunnel
# Do work
# Kill tunnel
How do I keep track of the tunnel process, so I know which one to kill?
You can do this cleanly with an ssh 'control socket'. To talk to an already-running SSH process and get it's pid, kill it etc. Use the 'control socket' (-M for master and -S for socket) as follows:
$ ssh -M -S my-ctrl-socket -fNT -L 50000:localhost:3306 jm#sampledomain.com
$ ssh -S my-ctrl-socket -O check jm#sampledomain.com
Master running (pid=3517)
$ ssh -S my-ctrl-socket -O exit jm#sampledomain.com
Exit request sent.
Note that my-ctrl-socket will be an actual file that is created.
I got this info from a very RTFM reply on the OpenSSH mailing list.
You can tell SSH to background itself with the -f option but you won't get the PID with $!.
Also instead of having your script sleep an arbitrary amount of time before you use the tunnel, you can use -o ExitOnForwardFailure=yes with -f and SSH will wait for all remote port forwards to be successfully established before placing itself in the background. You can grep the output of ps to get the PID. For example you can use
...
ssh -Cfo ExitOnForwardFailure=yes -N -L 9999:localhost:5900 $REMOTE_HOST
PID=$(pgrep -f 'N -L 9999:')
[ "$PID" ] || exit 1
...
and be pretty sure you're getting the desired PID
You can tell ssh to go into background with & and not create a shell on the other side (just open the tunnel) with a command line flag (I see you already did this with -N).
Save the PID with PID=$!
Do your stuff
kill $PID
EDIT: Fixed $? to $! and added the &
I prefer to launch a new shell for separate tasks and I often use the following command combination:
$ sudo bash; exit
or sometimes:
$ : > sensitive-temporary-data.txt; bash; rm -f sensitive-temporary-data.txt; exit
These commands create a nested shell where I can do all my work; when I'm finished I hit CTRL-D and the parent shell cleans up and exits as well. You could easily throw bash; into your ssh tunnel script just before the kill part so that when you log out of the nested shell your tunnel will be closed:
#!/bin/bash
ssh -nNT ... &
PID=$!
bash
kill $PID
You could launch the ssh with a & a the end, to put it in the background and grab its id when doing. Then you just have to do a kill of that id when you're done.
A simple bash script to solve your problem.
# Download then put in $PATH
wget https://raw.githubusercontent.com/ijortengab/bash/master/commands/command-keep-alive.sh
mv command-keep-alive.sh -t /usr/local/bin
# open tunnel, put script in background
command-keep-alive.sh "ssh -fN -o ServerAliveInterval=10 -o ServerAliveCountMax=2 -L 33306:localhost:3306 myserver" /tmp/my.pid &
# do something
mysql --port 33306
# close tunnel
kill $(cat /tmp/my.pid)
https://github.com/aronpc/remina-ssh-tunnel
#!/usr/bin/env sh
scriptname="$(basename $0)"
actionname="$1"
tunnelname=$(echo "$2" | iconv -t ascii//TRANSLIT | sed -E 's/[^a-zA-Z0-9-]+/-/g' | sed -E 's/^-+|-+$//g' | tr A-Z a-z)
remotedata="$3"
tunnelssh="$4"
if [ $# -lt 4 ]
then
echo "Usage: $scriptname start | stop LOCAL_PORT:RDP_IP:RDP_PORT SSH_NODE_IP"
exit
fi
case "$actionname" in
start)
echo "Starting tunnel to $tunnelssh"
ssh -M -S ~/.ssh/sockets/$tunnelname.control -fnNT -L $remotedata $tunnelssh
ssh -S ~/.ssh/sockets/$tunnelname.control -O check $tunnelssh
;;
stop)
echo "Stopping tunnel to $tunnelssh"
ssh -S ~/.ssh/sockets/$tunnelname.control -O exit $tunnelssh
;;
*)
echo "Did not understand your argument, please use start|stop"
;;
esac
usage example
Edit or create new remmina server connection
schema
~/.ssh/rdp-tunnel.sh ACTION TUNNELNAME LOCAL_PORT:REMOTE_SERVER:REMOTE_PORT TUNNEL_PROXY
name
description
ACTION
start|stop
TUNNELNAME
"string identify socket" slugify to create socket file into ~/.ssh/sockets/string-identify-socket.control
LOCAL_PORT
the door that will be exposed locally if we use the same port for two connections it will crash
REMOTE_SERVER
the ip of the server that you would access if you had it on the proxy server that will be used
REMOTE_PORT
the service port that runs on the server
TUNNEL_PROXY
the connection you are going to use as a proxy, it needs to be in your ~/.ssh/config preferably using the access keys
I use the combination (% g-% p) of the remmina group name and connection name to be my TUNNELNAME (this needs to be unique, it will see the socket name)
pre-command
~/.ssh/rdp-tunnel.sh start "%g-%p" 63394:192.168.8.176:3389 tunnel-name-1
post-command
~/.ssh/rdp-tunnel.sh stop "%g-%p" 63394:192.168.8.176:3389 tunnel-name-1
you can and should use this script to access anything, I use it constantly to access systems and services that do not have a public ip going through 1,2,3,4,5 or more ssh proxies
see more into :
ssh config
ssh mach
ssh jump hosts
sshuttle python ssh
Refs:
https://remmina.org/remmina-rdp-ssh-tunnel/
https://kgibran.wordpress.com/2019/03/13/remmina-rdp-ssh-tunnel-with-pre-and-post-scripts/
Bash script to set up a temporary SSH tunnel
https://gist.github.com/oneohthree/f528c7ae1e701ad990e6