In this section:

Overview

The Screen utility is a tool for use with Linux that connects a physical terminal between several shell processes. This utility is included with all Linux-based Ribbon products.

 

Ribbon recommends using the Screen utility when working remotely on a server, especially during install, upgrade or migration activities.

The Screen utility allows you to:

  • Use multiple shell windows from a single SSH session.
  • Keep a shell active during network disruptions.
  • Disconnect and re-connect to a shell session from multiple locations.
  • Run a lengthy process without maintaining an active shell session.
  • Copy-and-Paste text between windows and so on.

All windows run their programs completely independent of each other. Whatever you type is sent to the program running in the current window. To initiate the command, use Ctrl-A. This is usually followed by another keystroke depending on what you do next.

For more information on the Screen utility, refer to http://www.gnu.org/software/screen/manual/screen.html.

Installing the Screen

Download the screen-4.0.3-4.el5.x86_64.rpm file (only in case of RedHat 5.x releases) from the LINTEL_PLATFORM area of Sonus SalesForce Customer Portal. Copy the downloaded .rpm file into /tmp directory of the Linux server. 

 The Screen utility is installed by default with RedHat 6.x and later versions.

# cd /tmp
# rpm -ihv screen-4.0.3-4.el5.x86_64.rpm

To check if Screen is installed in your Linux system, execute the following command:

# which screen

/usr/bin/screen

The Screen utility is available by default under /usr/bin/screen or /bin/screen.

Starting Linux Screen

Execute the following command to start screen:

# screen

Screen Options

The Screen utility uses the Ctrl-A command to send commands to screen instead of the shell.

The following commands are used in combination with the Ctrl-A command:

OptionsKeystokeDescription
Help

Ctrl -A + ?

List the screen help page

Creating new window

Ctrl-A + C

Create a new window with your default prompt.
Creating window titleCtrl-A + A

Assign the screen window with a title.

Enter the screen window name as Scr1

Switching between windowsCtrl-A + NSwitch to the next window.
Ctrl-A + P

Switch to the previous window.

Ctrl-A + <1-9>

Switch to screen window number 0 to 9.

Example: Ctrl-A + 2, switches to the second screen window.

Detaching from screenCtrl-A  + D

Detach from a window and reattach later.

Reattach to screen

screen -r

To re-attach to your detached screen, execute this command.

If you have multiple screens you may get this:

Enter screen -r <screen name> to re-attach the required screen.

 

Logging screen outputsCtrl-A + H

Create a running log of the session to the file "hardcopy.n" file (where n is the number of the current window).

The hard copies are dumped in the screen's current working directory.

Getting alerts
 
Ctrl-A + M

Monitor a window for activity.

Example:

If you are waiting for output from a long-running program, you can use Ctrl + a M to look for activity. The Screen utility will then flash an alert at the bottom of the page when output is registered on that screen.

If you are downloading a large file or compiling a program, you can be notified when there is no more output.

Locking screen sessionCtrl-A + X

Lock your screen session. This requires a password to access the session again.

Stopping screenexit

To exit and close the screen utility, execute this command.

Kill the screenCtrl-A + K

Terminate and exit the screen utility.

Type y to terminate the screen.