Change GNUS Screen Caption Colors Based on Window Activity for SSH Sessions on Production Machine

Change GNU Screen Command Line Colors Based on Window Activity for SSH Sessions on Production Machines

When working with SSH sessions on production machines, it is often useful to have visual cues to quickly identify the current window and any important activity. One way to do this is by changing the color of the command line caption in GNU Screen based on the window activity. This article will cover the key concepts and steps for making this change, with a focus on production machines.

GNU Screen Overview

GNU Screen is a terminal multiplexer that allows users to run multiple terminal sessions within a single window. This is especially useful for SSH sessions on production machines, where users may need to run multiple commands or processes simultaneously.

Changing the Command Line Caption

In GNU Screen, the command line caption is the text that appears at the bottom of the terminal window. By default, it displays the window title and the current command. However, it can be customized using the caption command in the .screenrc file.

Changing Colors Based on Window Activity

To change the color of the command line caption based on window activity, we will use the %{..%} format in the caption command. This format allows us to insert special escape sequences that control the color and appearance of the text. Specifically, we will use the %w and %c sequences, which represent the current window and the window with the most recent activity, respectively.

Preferred Colors: Green and Red

For this example, we will use green and red as the preferred colors for the command line caption. Green will be used for the current window, and red will be used for the window with the most recent activity. These colors were chosen for their high contrast and easy visibility, making them ideal for production machines.

Implementation

To implement this feature, we need to edit the .screenrc file and add the following lines:

The key parts of this command are:

• %{.bW}: This sets the background color of the entire caption to white.
• %-w and %+w: These sequences represent the width of the window with the current activity and the total window width, respectively. By setting the color of the space between them, we can create a visible separation between the current window and the rest of the windows.
• %n: This displays the window number of the current window.
• %t: This displays the title of the current window.
• %{.yW}: This sets the background color of the space after the current window to yellow.
• %c: This displays the title of the window with the most recent activity.
• %{..G}, %{..R}, and %{..Y}: These sequences set the color of the text that follows them to green, red, and yellow, respectively.

By following the steps outlined in this article, you can change the color of the command line caption in GNU Screen based on window activity for SSH sessions on production machines. This can provide a valuable visual cue for quickly identifying the current window and any important activity, making it an ideal feature for production machines.

References

• Controlling the Caption
• Using GNU Screen for Terminal Multiplexing
• Change screen status line color when a window has received output but is not current