Setup box

Long Running Sessions

Using solutions like screen or mosh can help workaround ssh hang-ups which can kill any child processes of an active ssh session.

Screen

• How do I start screen, during an active ssh session?

  • screen

    • will start a screen session with a random name

    • screen -S SESSIONNAME is good for starting a session with a name

• How do I list any pre-existing screen sessions?

  • screen -ls

• How to I re-attach or re-join a previous session?

  • screen -r previous_session_name

• How do I force detach and then reattach a previous session?

  • screen -d -r previous_session_name

• How do I rename a pre-existing screen session?

  • screen -S old_session_name -X sessionname new_session_name

• How to check if I'm in a screen session?

  • echo $STY

    • If you are inside a screen session, the output will be the session name

    • otherwise, the output will be empty

• How do I find my current screen session's name?

  • echo $STY

• How do I kill a screen session?

  • screen -X -S <SESSION_ID> quit

• How do I kill my current screen session?

    screen -X -S `echo -n $STY` quit

• How do I scroll?

  • Inside the screen session you can use: CTRL+A (release), [

    • You can then use the arrows to scroll around the window. To get out of scrolling you can use CTRL+C

  • Ctrl + A, ESC and then vim-like commands: Ctrl + u or Ctrl + d

  • You can modify .screenrc to allow mouse-based scrollback.

      # added on july 19 2017 by pulkit
      # after editing the source from: https://gist.github.com/ChrisWills/1337178
    ​
      # GNU Screen - main configuration file
      # All other .screenrc files will source this file to inherit settings.
      # Author: Christian Wills - [email protected]
    ​
      # Allow bold colors - necessary for some reason
      attrcolor b ".I"
    ​
      # Tell screen how to set colors. AB = background, AF=foreground
      termcapinfo xterm 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm'
    ​
      # Enables use of shift-PgUp and shift-PgDn
      termcapinfo xterm|xterms|xs|rxvt [email protected]:[email protected]
    ​
      # Erase background with current bg color
      defbce "on"
    ​
      # Enable 256 color term
      term xterm-256color
    ​
      # Cache 999999 lines for scroll back
      defscrollback 999999
    ​
      hardstatus alwayslastline
    ​
      # Very nice tabbed colored hardstatus line
      hardstatus string '%{= Kd} %{= Kd}%-w%{= Kr}[%{= KW}%n %t%{= Kr}]%{= Kd}%+w %-= %{KG} %H%{KW}|%{KY}%101`%{KW}|%D %M %d %Y%{= Kc} %C%A%{-}'
    ​
      # Hide hardstatus: ctrl-a f
      bind f eval "hardstatus ignore"
    ​
      # Show hardstatus: ctrl-a F
      bind F eval "hardstatus alwayslastline"