Tjyylli

I have been reading about how to automatically start a screen when I ssh to a remote server. I would like a simple one-liner to add to my .bash_profile to start screen when I ssh in, and NOT exit my remote connection when I detach the screen.

I have been looking into exec screen and pretty much every combination of -d, -r, -D and -R and cannot figure out what flags I need.

Ideally I would type ssh whatever and be logged into the server in a new screen or it can reattach an old screen, I would kind of like to know how to do both to see which I like better. Then I can either type Ctrl ad or Ctrl d and have it bring me back to the normal ssh login for that server (where you would see the motd). From there I can screen -r back into whatever screen I want, or hit Ctrl d again to log out.

A simple screen -R should do the trick.

To verify this, I added screen -R to my .bash_profile on a remote server, logged in, detached from screen, and was dropped back to a normal shell prompt on the remote server. Verified with .bashrc as well. Subsequent logins yielded the expected result (re-attach to screen session).

I had issues with 40 cascading screen sessions being created with some of the solutions when starting a new window or screen session. I was able to eliminate the cascading screen and create a new session if one didn't exist with this:

if [ -z "$STY" ]; then screen -R; fi

It tests whether you're in a screen session and runs screen -R if you aren't. Without the test you get the "Attaching from inside of screen?" warning from screen each time you create a new screen window.

If I understand your need, you should try :

if $(screen -ls | grep -q pts); then screen -x; else screen -R; fi

It will create only one screen session, otherwise it will reconnect to the existing one in a multi-windows fashion ( even if you have multiple ssh session, you will end up to the same screen session )

screen -RR will reattach to the first available session or create one if necessary.

Here a little extension,

the script for the bashrc check if there is more than one detached screen session. If there is more, then you must choose the session manualy.
Whene there is a detached session, you come back to this session.
If you exit the session then the ssh session will close up too.

 #Start Screen

 if [ -z "$STY" ]; then



 value=$( screen -ls |grep '<pts.*Detached>' |wc -l )



 if [ $value -gt 1 ]; then



  screen -ls



 else



  screen -R



  echo 5 Sek. bis die SSH Session beendet wird.



  echo Strg + C - um ohne screen weiter zu arbeiten.



  sleep 6



  exit



 fi



fi

If you want to connect automatically to a screen session when you connect via SSH, add the code below to your .bash_profile or your .bashrc on your remote machine, it will:

• Start a new screen session every time you connect through SSH.


• Re-use already existing detached screen session, always starting with the latest one. If no detached sessions available it starts a new one.


• When you open multiple SSH connections to your machine you will get a different screen session since we are only re-using detached ones.


• Avoid loops in case you are adding the script to your .bashrc
  

Here is the script:

#!/bin/bash

#

#  Attaches to the first Detached Screen. Otherwise starts a new Screen.



# Only run if we are not already inside a running screen and only if in an SSH session.

if [[ -z "${STY}" && ! -z "${SSH_CLIENT}" ]]; then

  detached_screens=($(screen -ls | grep pts | grep -v Attached))



  for screen in "${detached_screens[@]}"; do

    if [[ "${screen}" == *".pts"* ]]; then

      IFS='.pts' read -ra split <<< "${screen}"

      for id in "${split[@]}"; do

        first_id="${id}"

        break

      done 

      break

    fi

  done



  screen -R $first_id

fi

PS: If you would like to enable this for local terminal, remove && ! -z "${SSH_CLIENT} on the first line.