Just writing a quick loop to list out existing tmux sessions when I log into a server, depending on whether tmux is installed (via .bashrc on CentOS).
if rpm -q tmux; then
echo -e "TMUX sessions running:\n"
echo `tmux ls`
fi
This works great when tmux has a session or two, but if there are no running tmux sessions, I'm getting failed to connect to server: No such file or directory.
Is there a way to suppress this?
Thanks!
Note that you may have a tmux server running, but you cannot connect to it because someone cleaned out the /tmp directory and took the server's socket with it.
In that case, you can tell the server to recreate the socket by sending it a SIGUSR1 signal.
% ps aux | grep -w [t]mux
root 14799 0.2 0.0 36020 488 ? Ss May08 51:30 tmux
% kill -USR1 14799
% tmux ls
<list of tmux sessions>
Using a combination of #Barmar and #Etan Reisner 's advice:
tmux ls 2> /dev/null
Nothing is echoed in when there are no sessions, otherwise the list is reported.
Related
On a remote machine, I have a tmux session with ID selu, and I am running a python program
python test.py that runs a C++ program main.cpp with different parameters several times. I want to learn the parameters of C++ program running at the moment in that session. How can I do this?
You can rely on the run-shell command. Here is an example of how to grep the current active process of the active pane.
bind-key M-v run-shell 'T=$(tmux display -p "#{pane_tty}" | sed "s=/dev/=="); if pgrep -t$T "fzf|vim|elvish" &> /dev/null; then tmux send-key M-v; elif pgrep -t$T "gdb" &> /dev/null; then tmux send-key PageUp; else tmux copy-mode; fi'
You can also add -t <your session> to run-shell in order to specify the needed session.
new here have learned tons over the years and happen to have a pretty puzzling question. I just purchased a product to help edit photos in Adobe Lightroom. Its called a Loupedeck. Comes with software and is a device that controls all the parameters in Lightroom (makes editing way quicker)
Once I installed their loupdeck software and opened Lightroom I immediately got this prompt.
"Loupedeck needs access to tcp ports 23515 and 23516.
Other process is currently occupying 23515.
Loupedeck will not work until that application is closed."
I have been searching for days trying to find what app I have installed thats using or used port 23515. I have tried checking in terminal with the simple netstat command, and found nothing. I've used little snitch to see if any programs are using that port, still nothing. Im a little lost and sadly the company is also lost and has no advice.
Computer - Macbook pro 2011 17" 2.3ghz OSX 10.12.6
Here is the error in Lightroom
From this answer:
lsof -n -i4TCP:23515
lsof -n -i TCP:23515 | grep LISTEN
lsof -n -i:23515 | grep LISTEN
Netstat may also work:
netstat -ap tcp | grep -i "23515"
Any of these commands should give you the name and PID of the process.
Once you have the PID, you can kill the process, or if you know the process name is process_name you can use killall -KILL process_name .
Just for the record though, your terminal isn't running an administrative shell by default. In order to execute commands in terminal as an administrator, you have to use the command sudo su and then enter your password. Once you have a prompt with a #, you can try these commands again, just to be sure.
In one command find and kill:
kill -9 `lsof -i : 23515 -t` or if the existing process was launched by root or an other user: sudo kill -9 `lsof -i : 23515 -t`
lsof -i : 23515 returns the process id using the port 23515 on your machine.
You may also want to restart your computer, just in case the process using this port went into a "zombie" mode or lock the port and went off without freeing the port.
You can try to fine the process listening to those ports:
lsof -i :23515 -t
If you want to save time in the long run, you can add this script "kill-process.sh" into your /usr/local/bin
#!/bin/bash
echo Killing process..
usage() { echo "Usage: $0 [-p <port-number>]" 1>&2; exit 1; }
while getopts ":p:" o; do
case "${o}" in
p)
p=${OPTARG}
((p > 0 )) || usage
;;
*)
usage
;;
esac
done
shift $((OPTIND-1))
if [ -z "${p}" ]; then
usage
fi
PID=$(lsof -ti:$p)
if [ -z "${PID}" ]; then
echo "No process running on port ${p}"
else
kill $PID
echo "Killed process PID: ${PID}"
fi
Add this line into your .zshrc
alias kill-process="sh /usr/local/bin/kill-process.sh"
Then just run from your terminal
kill-process -p 23515
You will save time in the long run and this is useful if you need to close any process in any port by specifying it as a parameter.
So I have a problem similar to how to send ssh job to background.
I have a windows c# program automated to execute tcpdump on a remote linux os using http://sshnet.codeplex.com/. I'm trying to execute tcpdump on the remote linux and leave it running after I disconnect.
I've been doing a lot of debugging using plink, but cannot seem to achieve the desired result. I've tried:
plink root#10.5.1.1 bash -c "tcpdump -i eth0 -w test.cap"
but it holds the sshclient until I ctrl+C (not going to work for automated solution). I've also tried variations of:
plink root#10.5.1.1 bash -c "tcpdump -i eth0 -w test.cap &"
but either the command is not executed at all (test.cap does not exist) or is terminated immediately (test.cap contains 1 line). During testing, I've left a ping going, so the capture should have somthing...
The previously mentioned link solves the problem with screen, but the remote linux os is not configurable and does not have screen. Any suggestions are welcome.
In the latter case, your tcpdump process is probably being aborted when you disconnect. Try:
plink root#10.5.1.1 bash -c "nohup tcpdump -i eth0 -w test.cap &"
See the manpage for nohup. You may also want to consider redirecting stdout and stderr to a file or /dev/null to prevent nohup from writing output to a file:
plink root#10.5.1.1 bash -c "nohup tcpdump -i eth0 -w test.cap >/dev/null 2>&1 &"
I had a similar problem while starting a remote application. This pattern worked for me on Debian servers:
ssh root#server "nohup /usr/local/bin/app -c cfg &; exit"
addition: for another test the above didn't work, ie. the command didn't start on the remote server. Adding a command that returns successfully before the exit seems to work.
ssh root#server "nohup /usr/local/bin/otherapp &; w; exit"
I had a similar situation:
(on windows machine) i wanted to create a ms batch script to open an SSH connection to a raspberry pi and execute a local script in the background.
I found that combining both Raj's and fahd's answers did the trick for me:
my ms batch script:
plink -load "raspberry Pi" -t -m startCommand.txt
the content of startCommand.txt is as follows:
nohup /home/pi/myscript >/dev/null 2>&1 &
w
exit
The ">/dev/null 2>&1 " is important!
I found out (the hard way) that the RPi's SDcard kept getting full by an extremely large nohup.out file (and with a full SDcard, the RPi couldn't even login properly)
reasoning:
I used the -load to load a saved session in PuTTY (i do this because i am authenticating with public/private keys instead of passwords, but this should be the same as simply typing in the host)
then -t (as recommended by Raj)
then -m to load a list of commands in that file
without the parameter "-t" and without the "w" and "exit", my batch script would just run, not execute 'myscript' and close again.
I had the same issue. I had a scrip in which I had nohup tcpdump .... & . I could not use ssh to run it as it dies when the ssh finished. The solution I came up with was super simple. I just added sleep 5 to the end of my script and it works just fine. It seems tcpdump needs some seconds to go to background safely before you exit even with nohup.
I had the same problem, and I found that the "-t" option seems to be important to nohup. I found the nohup wasn't taking affect without the "-t" option.
ssh -t user#remote 'nohup tcpdump -i any -w /tmp/somefile &>/dev/null & sleep 2'
I think that I've nailed it, at least in IBM AIX
I'm using
ssh -tq user#host "/path/start-tcpdump.ksh"
(authentication is done by publick key).
I was having inconsistent results using simple "nohup tcpdump .... &", sometimes it worked, sometimes it did not, sometimes it even blocked and I had to disconnect the session.
So far, this is working ok, I can't really say WHY it is working, but it is...
This is my start-tcpip.ksh
#!/usr/bin/ksh
HOST=$(uname -n)
FILTER="port not 22"
(tcpdump -i en1 -w $HOST-en1.cap $FILTER >/dev/null 2>&1 ) &
sleep 2
(tcpdump -i en2 -w $HOST-en2.cap $FILTER >/dev/null 2>&1 ) &
sleep 2
exit 0
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
I am using the program synergy together with an ssh tunnel
It works, i just have to open an console an type these two commands:
ssh -f -N -L localhost:12345:otherHost:12345 otherUser#OtherHost
synergyc localhost
because im lazy i made an Bash-Script which is run with one mouseclick on an icon:
#!/bin/bash
ssh -f -N -L localhost:12345:otherHost:12345 otherUser#OtherHost
synergyc localhost
the Bash-Script above works as well, but now i also want to kill synergy and the ssh tunnel via one mouseclick, so i have to save the PIDs of synergy and ssh into file to kill them later:
#!/bin/bash
mkdir -p /tmp/synergyPIDs || exit 1
rm -f /tmp/synergyPIDs/ssh || exit 1
rm -f /tmp/synergyPIDs/synergy || exit 1
[ ! -e /tmp/synergyPIDs/ssh ] || exit 1
[ ! -e /tmp/synergyPIDs/synergy ] || exit 1
ssh -f -N -L localhost:12345:otherHost:12345 otherUser#OtherHost
echo $! > /tmp/synergyPIDs/ssh
synergyc localhost
echo $! > /tmp/synergyPIDs/synergy
But the files of this script are empty.
How do I get the PIDs of ssh and synergy?
(I try to avoid ps aux | grep ... | awk ... | sed ... combinations, there has to be an easier way.)
With all due respect to the users of pgrep, pkill, ps | awk, etc, there is a much better way.
Consider that if you rely on ps -aux | grep ... to find a process you run the risk of a collision. You may have a use case where that is unlikely, but as a general rule, it's not the way to go.
SSH provides a mechanism for managing and controlling background processes. But like so many SSH things, it's an "advanced" feature, and many people (it seems, from the other answers here) are unaware of its existence.
In my own use case, I have a workstation at home on which I want to leave a tunnel that connects to an HTTP proxy on the internal network at my office, and another one that gives me quick access to management interfaces on co-located servers. This is how you might create the basic tunnels, initiated from home:
$ ssh -fNT -L8888:proxyhost:8888 -R22222:localhost:22 officefirewall
$ ssh -fNT -L4431:www1:443 -L4432:www2:443 colocatedserver
These cause ssh to background itself, leaving the tunnels open. But if the tunnel goes away, I'm stuck, and if I want to find it, I have to parse my process list and home I've got the "right" ssh (in case I've accidentally launched multiple ones that look similar).
Instead, if I want to manage multiple connections, I use SSH's ControlMaster config option, along with the -O command-line option for control. For example, with the following in my ~/.ssh/config file,
host officefirewall colocatedserver
ControlMaster auto
ControlPath ~/.ssh/cm_sockets/%r#%h:%p
the ssh commands above, when run, will leave spoor in ~/.ssh/cm_sockets/ which can then provide access for control, for example:
$ ssh -O check officefirewall
Master running (pid=23980)
$ ssh -O exit officefirewall
Exit request sent.
$ ssh -O check officefirewall
Control socket connect(/home/ghoti/.ssh/cm_socket/ghoti#192.0.2.5:22): No such file or directory
And at this point, the tunnel (and controlling SSH session) is gone, without the need to use a hammer (kill, killall, pkill, etc).
Bringing this back to your use-case...
You're establishing the tunnel through which you want syngergyc to talk to syngergys on TCP port 12345. For that, I'd do something like the following.
Add an entry to your ~/.ssh/config file:
Host otherHosttunnel
HostName otherHost
User otherUser
LocalForward 12345 otherHost:12345
RequestTTY no
ExitOnForwardFailure yes
ControlMaster auto
ControlPath ~/.ssh/cm_sockets/%r#%h:%p
Note that the command line -L option is handled with the LocalForward keyword, and the Control{Master,Path} lines are included to make sure you have control after the tunnel is established.
Then, you might modify your bash script to something like this:
#!/bin/bash
if ! ssh -f -N otherHosttunnel; then
echo "ERROR: couldn't start tunnel." >&2
exit 1
else
synergyc localhost
ssh -O exit otherHosttunnel
fi
The -f option backgrounds the tunnel, leaving a socket on your ControlPath to close the tunnel later. If the ssh fails (which it might due to a network error or ExitOnForwardFailure), there's no need to exit the tunnel, but if it did not fail (else), synergyc is launched and then the tunnel is closed after it exits.
You might also want to look in to whether the SSH option LocalCommand could be used to launch synergyc from right within your ssh config file.
Quick summary: Will not work.
My first idea is that you need to start the processes in the background to get their PIDs with $!.
A pattern like
some_program &
some_pid=$!
wait $some_pid
might do what you need... except that then ssh won't be in the foreground to ask for passphrases any more.
Well then, you might need something different after all. ssh -f probably spawns a new process your shell can never know from invoking it anyway. Ideally, ssh itself would offer a way to write its PID into some file.
just came across this thread and wanted to mention the "pidof" linux utility:
$ pidof init
1
You can use lsof to show the pid of the process listening to port 12345 on localhost:
lsof -t -i #localhost:12345 -sTCP:listen
Examples:
PID=$(lsof -t -i #localhost:12345 -sTCP:listen)
lsof -t -i #localhost:12345 -sTCP:listen >/dev/null && echo "Port in use"
well i dont want to add an & at the end of the commands as the connection will die if the console wintow is closed ... so i ended up with an ps-grep-awk-sed-combo
ssh -f -N -L localhost:12345:otherHost:12345 otherUser#otherHost
echo `ps aux | grep -F 'ssh -f -N -L localhost' | grep -v -F 'grep' | awk '{ print $2 }'` > /tmp/synergyPIDs/ssh
synergyc localhost
echo `ps aux | grep -F 'synergyc localhost' | grep -v -F 'grep' | awk '{ print $2 }'` > /tmp/synergyPIDs/synergy
(you could integrate grep into awk, but im too lazy now)
You can drop the -f, which makes it run it in background, then run it with eval and force it to the background yourself.
You can then grab the pid. Make sure to put the & within the eval statement.
eval "ssh -N -L localhost:12345:otherHost:12345 otherUser#OtherHost & "
tunnelpid=$!
Another option is to use pgrep to find the PID of the newest ssh process
ssh -fNTL 8073:localhost:873 otherUser#OtherHost
tunnelPID=$(pgrep -n -x ssh)
synergyc localhost
kill -HUP $tunnelPID
This is more of a special case for synergyc (and most other programs that try to daemonize themselves). Using $! would work, except that synergyc does a clone() syscall during execution that will give it a new PID other than the one that bash thought it has. If you want to get around this so that you can use $!, then you can tell synergyc to stay in the forground and then background it.
synergyc -f -n mydesktop remoteip &
synergypid=$!
synergyc also does a few other things like autorestart that you may want to turn off if you are trying to manage it.
Based on the very good answer of #ghoti, here is a simpler script (for testing) utilising the SSH control sockets without the need of extra configuration:
#!/bin/bash
if ssh -fN -MS /tmp/mysocket -L localhost:12345:otherHost:12345 otherUser#otherHost; then
synergyc localhost
ssh -S /tmp/mysocket -O exit otherHost
fi
synergyc will be only started if tunnel has been established successfully, which itself will be closed as soon as synergyc returns.
Albeit the solution lacks proper error reporting.
You could look out for the ssh proceess that is bound to your local port, using this line:
netstat -tpln | grep 127\.0\.0\.1:12345 | awk '{print $7}' | sed 's#/.*##'
It returns the PID of the process using port 12345/TCP on localhost. So you don't have to filter all ssh results from ps.
If you just need to check, if that port is bound, use:
netstat -tln | grep 127\.0\.0\.1:12345 >/dev/null 2>&1
Returns 1 if none bound or 0 if someone is listening to this port.
There are many interesting answers here, but nobody mentioned that the manpage of SSH does describe this exact case! (see TCP FORWARDING section). And the solution they offer is much simpler:
ssh -fL 12345:localhost:12345 user#remoteserver sleep 10
synergyc localhost
Now in details:
First we start SSH with a tunnel; thanks to -f it will initiate the connection and only then fork to background (unlike solutions with ssh ... &; pid=$! where ssh is sent to background and next command is executed before the tunnel is created). On the remote machine it will run sleep 10 which will wait 10 seconds and then end.
Within 10 seconds, we should start our desired command, in this case synergyc localhost. It will connect to the tunnel and SSH will then know that the tunnel is in use.
After 10 seconds pass, sleep 10 command will finish. But the tunnel is still in use by synergyc, so SSH will not close the underlying connection until the tunnel is released (i.e. until synergyc closes socket).
When synergyc is closed, it will release the tunnel, and SSH in turn will terminate itself, closing a connection.
The only downside of this approach is that if the program we use will close and re-open connection for some reason then SSH will close the tunnel right after connection is closed, and the program won't be able to reconnect. If this is an issue then you should use an approach described in #doak's answer which uses control socket to properly terminate SSH connection and uses -f to make sure tunnel is created when SSH forks to the background.