ssh and shell through ssh : how to exit?

Question

I'm launching a distant script through SSH like this:

ssh user@ipaddress '~/my_script.sh'

Everything is going fine but once the script is finished, the connection is not closed. I Have to press CTRL-C to break the current connection.

I've tried the "exit" command in '~/my_script.sh' and it's useless. I've tried the "logout" command in '~/my_script.sh' and I get a message:

logout: not login shell: use exit

...

Any idea how I could do to close automatically and properly the SSH once the script is done?

(Modification for clarification :) Here's what's inside my script :

#!/bin/sh
path_sources_qas=/sources/QuickAddress/
path_qas_bin=/usr/bin/qas

umount_disque_qas()
{
  # Umount du disque 'qas' s'il n'avait pas été 'umount' :
  nom_disque_monte=`cat /etc/mtab | grep qas | awk '{ print $2}'`
  if [ "$nom_disque_monte" != "" ]
  then
    echo "For safety, umount : $nom_disque_monte"
    umount $nom_disque_monte
  fi

}

# Umount twice (we never know if a st***d guy mounted it twice) :
umount_disque_qas
umount_disque_qas

echo "--------------------------------"
echo "Install ISO quick address..."
nom_fichier_iso=`ls -t $path_sources_qas | awk '{if (NR==1) {print $1}}'`
echo "Mount disk $nom_fichier_iso..."
mount -o loop -t iso9660 $path_sources_qas/$nom_fichier_iso /mnt/qas
echo "Done."

# All the folders are like this :
# /usr/bin/qas/Data.old.10
# /usr/bin/qas/Data.old.11
# /usr/bin/qas/Data.old.12
# ...

echo "--------------------------------"
echo "Stopping QuickAdress server..."
cd $path_qas_bin/apps/
./wvmgmtd shutdown qaserver:2021
sleep 3
echo "Done."

# Get last number of the folder:
num_dernier_dossier_backup=`ls -Atd $path_qas_bin/Data.old* | awk '{if (NR==1) {print $1}}' | awk -F . '{print $NF}'`
# Add 1 :
let "num_dernier_dossier_backup += 1"
# Full name :
nom_dossier_backup=Data.old.$num_dernier_dossier_backup
echo "--------------------------------"
echo "Saving Data to $nom_dossier_backup..."
cd $path_qas_bin
mv Data $nom_dossier_backup
echo "Done."


echo "--------------------------------"
echo "Copying new folder Data..."
cd $path_qas_bin
cp -r /mnt/qas/Data .
echo "Done."

echo "--------------------------------"
echo "Deleting unused datas..."
cd $path_qas_bin/apps/
rm -f $path_qas_bin/Data/frxmos.dap
echo "Done."

echo "--------------------------------"
echo "Restart server..."
cd $path_qas_bin/apps/
./qaswvd &
sleep 3
echo "Done."
sleep 3

echo "--------------------------------"
echo "Check: server state: you should read 'OK':"
./wvmgmtd srvlist
echo "Done."

echo "--------------------------------"
echo "Check: active licences (only one here):"
./wvmgmtd licencelistread qaserver:2021
echo "Done."

echo "--------------------------------"
echo "Check: counters: number of addresses left:"
./wvmgmtd counterinforead qaserver:2021
echo "Done."

echo "--------------------------------"
echo "Check: Datasets avalaibles:"
./wvmgmtd datalistread current qaserver:2021
echo "Done."

echo "--------------------------------"
echo "Check: "meters" for "licence by click":"
./wvmgmtd meterslistread current qaserver:2021
echo "Done."

echo "--------------------------------"
echo "Removing virtual disk..."
umount_disque_qas
echo "Done."

echo "All done"
echo "Click 'Ctrl-C' to quit."

exit

When I launch it through SSH, it runs and at the end, I read "All done." so this means it reaches the last 2 lines.

Any idea how I could do to close automatically and pr

Answer 1

The exit in the shell script does not work because it is exiting from the script, not the shell. To exit from the shell after the script completes do

ssh user@ipaddress '~/my_script.sh && exit'

This will run the script then exit from the shell.

Answer 2

The ssh connection remains open when the process started by ssh (here, a shell) exits, if there are other processes that are still using it. I don't know the exact rules that the ssh daemon follows, but a connection is in use, at least, if the standard output of any child process is still connected to the original pipe provided by ssh. Compare:

ssh somehost 'sleep 5 &'  # exits after 5 seconds
ssh somehost 'sleep 5 >/dev/null &'  # exits immediately seconds

When you start a daemon, you should background it and close its file descriptors. At least, use this:

./qaswvd </dev/null >/dev/null 2>/dev/null &

You may want to add nohup in front; it won't make a difference here but would be useful if the script was run from a terminal. Many programs that are designed to act as daemon have a command-line options to get them to fork, close file descriptors, ignore signals and other niceties. Check in the qaswvd documentation if it has one. You could also investigate “daemonizer” utilities.

Answer 3

I saw this post when I googled for the solution of the same situation. Although it's kinda late to solve @Oliver's problem, since the accepted answer was clearly not working either to OP or me (don't know why it's accepted), I'd still like to post my own solution for future googler. It's simple: add a -f option in ssh command:

ssh -f user@ipaddress '~/my_script.sh'

EDIT

The effect of -f option is to put ssh in the background, so without any further option added it is possible that the connection is still alive even it seems that it's broken. One may refer to the answer given in another post on this site if interested.

Answer 4

Like Ignacio, I'm curious to know what's in your script.

Perhaps you could try and reduce your script to the smallest possible example that produces the error condition.

Or start from an empty script and add a command at a time until you see the problem, then you'll know what command causes your script to lock up.

If the empty script causes you a problem, you might want to investigate your ssh configuration, for example, is .bash_logout or some such called on exit that may cause an issue?

Answer 5

You're going to need to kill your parent process from within your script.

kill -SIGHUP $PPID

Answer 6

You may probably use jobs in your script. If that is the case shell just waits for your jobs to be finished and doesn't want to detach itself.

I'm not gonna repost, just will forward you http://en.wikipedia.org/wiki/Nohup#Existing_jobs

Answer 7

The problem is likely the following line.

./qaswvd &

This command is probably still running and will keep the ssh pipe open until stdin and stdout & stderr are closed.

Use this instead:

./qaswvd </dev/null >/dev/null 2>&1 &