I have a bash script which need to start some process on remote machine.
I have done that using sshpass command.
I need to store the PID of that remote process.
I tried the following with a script:
sshpass -p password ssh user#ipaddr /bin/bash << EOF
nohup process > /dev/null 2>&1 & echo $! > pid_file
cat pid_file
EOF
when I check with remote machine, the process is started and pid_file also has a number written in it. But the process id and number of pid_file do not match.
Executing the above set of commands directly on terminal without script, doesn't write anything in pid_file.
Can somebody help in storing the right pid of remote process.
sshpass -p password ssh user#ipaddr /bin/bash << EOF
nohup process > /dev/null 2>&1 & echo $! > pid_file
cat pid_file
EOF
The thing is that $! get's expanded not on the remote computer, but on your computer. When using the Here document, variable names are replaced by their values. So it gets expanded to whatever process you have had run in the background on you computer. You need to execute echo $! on the remote computer. That's why it's good to use -c and to always properly enclose the arguments.
sshpass -p password ssh user#ipaddr /bin/bash -c 'nohup process >/dev/null 2>&1 & echo $! > pid_file'
or you can just escape the $!:
sshpass -p password ssh user#ipaddr /bin/bash <<EOF
nohup process > /dev/null 2>&1 & echo \$! > pid_file
cat pid_file
EOF
or the best is to use quoted here string delimiter:
sshpass -p password ssh user#ipaddr /bin/bash <<'EOF'
nohup process > /dev/null 2>&1 & echo $! > pid_file
cat pid_file
EOF
Related
The code manually is:
ssh -fNv -L 3049:localhost:2049 ubuntu#20.115.5.61
Now I have in /etc/rc.local:
#!/bin/bash
remote_host=ubuntu#20.115.5.61
remote_port=3049
local_port=2049
cmd="ssh -fN -R ${remote_port}:localhost:${local_port} ${remote_host}"
while true; do
pgrep -fx "$cmd" >/dev/null 2>&1 || $cmd
sleep 10
done
¿Help me?
Introduction
My question is very similar to this one, except that I'd like the output from the command to be redirected to a local file instead of a remote one.
The questioner was asking for a way to retrieve the process ID with a command similar to this one, where the mbuffer command wouldn't cause hanging:
read -r pid < <(ssh 10.10.10.46 "mbuffer -4 -v 0 -q -I 8023 > /tmp/mtest & echo $!"); echo $pid
The answerer responded with the following command to resolve the problem
read -r pid \
< <(ssh 10.10.10.46 'nohup mbuffer >/tmp/mtest </dev/null 2>/tmp/mtest.err & echo $!')
Which is really helpful but still places files on the remote machine, not the local one.
My Attempts
The following is my attempt to capture a log of the output of $command:
read -r PID < <(ssh $remote 'nohup $command >&2 & echo $!' 2> $log)
Which sets PID to the process ID properly but doesn't produce a log.
Question
How can I capture a log on my local machine of the stdout of my $command while still assigning PID to the process ID of $command?
Another approach:
{ read -r pid;
# Do whatever you want with $pid of the process on remote machine
cat > my_local_system_log_file
} <(ssh 10.10.10.46 "mkfifo /tmp/mtest; mbuffer -4 -v 0 -q -I 8023 &> /tmp/mtest & echo $!; cat /tmp/mtest");
Basically, the first line is PID & further lines are logs from the process.
I need a shell script that can take remote login in to a system and i can execute a bunch of commands in that system.
I made a script and actually it's working:
#!/bin/bash
USERNAME=KRUNAL
IP=10.61.162.241
ssh -l ${USERNAME} ${IP} "pwd "
ssh -l ${USERNAME} ${IP} "ls -la"
ssh -l ${USERNAME} ${IP} ./a.out
I have problem that if suppose i made script
ssh -l ${USERNAME} ${IP} "pwd " # this execute in remote system
ls -la # this execute in current system.
so every time i need ssh command to execute file on remote system.
Is there any way that i can run bunch of code in remote system with one time login.
You can send as much commands to ssh as you want, provided that you separate them with ; or linebreaks. So this should work:
ssh -l ${USERNAME} ${IP} "pwd; ls -la"
#Joao's suggestion works fine however its impractical when writing many lines.
If this is the case you can do
ssh -1 ${USERNAME} ${IP} bash << 'EOF'
cd /some/directory
./a.out
who am i
for i in `seq 1 10`
do
echo $i
done
EOF
Anything between 'EOF' and the final EOF will be executed in the server side.
You can also replace bash with csh or python and write code for that interpreter instead
If you want the output of the ssh session be stored in a file (say session.log) then replace
ssh -1 ${USERNAME} ${IP} bash << 'EOF'
with
ssh -1 ${USERNAME} ${IP} bash << 'EOF' > 'session.log'
rest remains unchanged
Here is my script.sh
for ((i=1; i<=400000; i++))
do
echo "loop $i"
echo
numberps=`ps -ef | grep php | wc -l`;
echo $numberps
if [ $numberps -lt 110 ]
then
php5 script.php &
sleep 0.25
else
echo too much process
sleep 0.5
fi
done
When I launch it with:
./script.sh > /dev/null 2>/dev/null &
that works except when I logout from SSH and login again, I cannot stop the script with kill%1 and jobs -l is empty
When I try to launch it with
nohup ./script.sh &
It just ouputs
nohup: ignoring input and appending output to `nohup.out'
but no php5 are running: nohup has no effect at all
I have 2 aleternatives to solve my problem:
1) ./script.sh > /dev/null 2>/dev/null &
If I logout from SSH and login again, How can I delete this job ?
or
2) How to make nohup run correctly ?
Any idea ?
nohup is not supposed to allow you to use jobs -l or kill %1 to kill jobs after logging out and in again.
Instead, you can
Run the script in the foreground in a GNU Screen or tmux session, which lets you log out, log in, reattach and continue the same session.
killall script.sh to kill all running instances of script.sh running on the server.
I'm creating a little bash script to copy new files from a windows machine to a remote linux centos server (i run this script using the git-shell) then i want to restart the python application thats running in the server to use those new files.
The problem is that everytime i run this script i want to end the actual running process before i start it again, so i want to get the pid of the process i start and save it to a file in the remote host so i can read it from there the next time i run the program and kill it.
My code by now looks similar to this:
echo "Copying code files to server..."
# The destination folder has to exist in the server
scp -r ./python/ root#myserver:/root/
echo "Checking for running processes..."
if ssh root#myserver 'ls dmr.pid >/dev/null'; then
echo "PID file exists, reading file..."
PID=$(ssh root#myserver 'cat dmr.pid')
# Terminate the actual process
echo "Terminating the process with PID '$PID'..."
ssh root#myserver 'kill $PID'
else
echo "PID file doesn't exist, not known processes running"
fi
# Restart the server and get the PID
echo "Restarting the server..."
ssh root#myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 &'
SERV_PID=$(ssh root#myserver 'echo $!')
echo "Saving PID to file dmr.pid"
ssh root#myserver "echo '$SERV_PID' > \"dmr.pid\""
echo "Sucesfully finished!"
The important lines are:
ssh root#myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 &'
SERV_PID=$(ssh root#myserver 'echo $!')
the problem with this is that the script finishes but the file ends up empty as well as the $SERV_PID variable.
And if i dont redirect the outputs and just do something like this:
SERV_PID=$(ssh root#myserver 'python /root/python/run_dev_server.py & echo $!')
i get stuck after "Restarting the server" and never get the PID or the file that will contain it or even the end of the script.
But if i run this right in the console:
ssh root#myserver 'python /root/python/run_dev_server.py & echo $!'
i get a PID printed to the terminal.
Any advice on this would be really appreciated.
ssh root#myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 &'
SERV_PID=$(ssh root#myserver 'echo $!')
With the above code, you are running two ssh commands and the both create two different shells. The problem is echo $! gives the most recent background process' ID from the current shell which is none.
That is, when you ssh for the second time, it's new shell and there's no background process running in it and hence echo $! gives no output. This explains why your PID file is empty.
Instead what you can do is to lookup for all instances of your python script and kill them using killall command. Or similar idea using ps command.
Thanks to Kingslndian i solved it by making one single command that did the three steps i required, so with that avoided the problem of running in different shells:
ssh root#myserver 'python /root/python/run_dev_server.py > /dev/null 2>&1 & echo $! > "dmr.pid"'