Revision as of 03:23, 7 January 2011

About screen

'screen' is a good tool for remote support.
It can also be used to start a command you want to keep running after you close your console session (you can later on attach to your running 'screen' session).

When you enter a 'screen' session you will not notice too much.
To know if you are inside a 'screen' session, use the notes in 'get help' section mentioned below.

Install

apk add screen

Use screen

Start a new session

screen

List existing sessions

screen -list

You might get a list that looks like this:

There are screens on:
        11151.pts-1.mhlab01     (Attached)
        11131.pts-3.mhlab01     (Attached)
2 Sockets in /var/run/screen/S-root.

Attach to a existing session

Lets say you want to attach to a existing session (e.g. the above "11131.pts-3.mhlab01" session).

screen -x 11131

or

screen -x pts-3

Close or kill a session

When you are inside a 'screen' session you can 'kill' it by using:

CTRL+A k

or you might just type:

exit

Get help

'screen' has various options/commands.
When your inside a 'screen' session you can get help and see what options you have by using:

CTRL+a ?

(Do not press/hold 'CTRL' when entering '?')

Extra

Force console users into a screen session

In some cases you might want to force only console users into a screen session.
Note that the this configuration will not force SSH-users into a screen.
Edit `/etc/profile` and add the following code to it:

if [ -n "$PS1" ] && [ -z "$STARTED_SCREEN" ] && [ -z "$SSH_TTY" ]; then
  STARTED_SCREEN=1 ; export STARTED_SCREEN
  screen -RR && exit 0
  echo "Screen failed! continuing with normal bash startup"
fi

Force console and SSH users into a screen session

The above example holds the if-statement:

&& [ -z "$SSH_TTY" ]

Remove this part from above configuration to force SSH sessions into a screen session.

Note: Console users will also be forced into a screen session when folowing these instructions

@@ Line 1: / Line 1: @@
-This document is a short note on how to monitor what's happening on the console.
+= About screen =
+'screen' is a good tool for remote support.<BR>
+It can also be used to start a command you want to keep running after you close your console session (you can later on attach to your running 'screen' session).
+When you enter a 'screen' session you will not notice too much.<BR>
+To know if you are inside a 'screen' session, use the notes in '[[#Get_help|get help]]' section mentioned below.
-'''Install programs'''
+= Install =
-  apk_add screen
+{{cmd|apk add screen}}
+= Use screen =
+== Start a new session ==
+{{cmd|screen}}
-'''Make it autostart'''
+== List existing sessions ==
+{{cmd|screen -list}}
-Lets edit '''/etc/profile''' and add the following code to it:
-  if [ -n "$PS1" ] && [ -z "$STARTED_SCREEN" ] && [ -z "$SSH_TTY" ]; then
-    STARTED_SCREEN=1 ; export STARTED_SCREEN
-    screen -RR && exit 0
-    echo "Screen failed! continuing with normal bash startup"
-  fi
-'''Not only the console...'''
-The above example holds the if-statement:
-  && [ -z "$SSH_TTY" ]
-This statement sees to that no ssh-sessions is forced into a screen.<BR>
-In case you want ssh-sessions to be forced into a screen, this option can be omitted.
-'''Check for available sessions'''
-To check what available screen-sessions are available:
-  screen -list
 You might get a list that looks like this:
-  There are screens on:
+<pre>
-.pts-1.mhlab01     (Attached)
+There are screens on:
-.pts-3.mhlab01     (Attached)
+.pts-1.mhlab01     (Attached)
-Sockets in /var/run/screen/S-root.
+.pts-3.mhlab01     (Attached)
+Sockets in /var/run/screen/S-root.
+</pre>
+== Attach to a existing session ==
+Lets say you want to attach to a existing session (e.g. the above "11131.pts-3.mhlab01" session).
+{{cmd|screen -x 11131}}
+or
+{{cmd|screen -x pts-3}}
-'''Attach to a session'''
+== Close or kill a session ==
+When you are inside a 'screen' session you can 'kill' it by using:
+{{cmd|CTRL+A k}}
+or you might just type:
+{{cmd|exit}}
-Lets say you want to attach to a existing session (e.g. the above "11131.pts-3.mhlab01" session).
+== Get help ==
-  screen -x pts-3
+'screen' has various options/commands.<BR>
+When your inside a 'screen' session you can get help and see what options you have by using:
+{{cmd|CTRL+a ?}}
+''(Do not press/hold 'CTRL' when entering ''''?'''')''
+= Extra =
+== Force console users into a screen session ==
+In some cases you might want to force only console users into a screen session.<BR>
+Note that the this configuration will not force SSH-users into a screen.<BR>
+Edit `/etc/profile` and add the following code to it:
+<pre>
+if [ -n "$PS1" ] && [ -z "$STARTED_SCREEN" ] && [ -z "$SSH_TTY" ]; then
+  STARTED_SCREEN=1 ; export STARTED_SCREEN
+  screen -RR && exit 0
+  echo "Screen failed! continuing with normal bash startup"
+fi
+</pre>
-'''Help'''
+== Force console and SSH users into a screen session ==
+The above example holds the if-statement:
-'screen' has various options/commands.<BR>
+ && [ -z "$SSH_TTY" ]
-When your inside a 'screen'-session you can:
+Remove this part from above configuration to force SSH sessions into a screen session.<BR>
-  CTRL+a ?
+{{Note|Console users will also be forced into a screen session when folowing these instructions}}
-(Don't hold CTRL when entering ''''?'''')