Howto: Linux desktop adjust sound or Linux volume control

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Q. How do I adjust Linux volume control?

A. You need to use a program called aumix to adjust sound / volume control. This program adjusts the settings of an audio mixing device. It can be used from the command line, in scripts, or interactively with the keyboard or mouse.

You can launch volume control as follows:
=> Click on Main Menu

=> Select Sound & Video

=> Now select Volume Control

aumix – command line program

Just type following command at shell prompt (open x terminal):
$ aumix
Output:

You can use following keys to control aumix sound settings:

  • page up, page down, up and down cursor: Select a new control.
  • Tab, Enter, , comma and period : Toggle between level and balance controls
  • + and – : Adjust the setting of the current device. The + and right cursor keys increase the level by 3%; the – and left cursor keys decrease it by the same amount.
  • S or s : Save settings to the rc file
  • U or u : Undo any muting
  • M or m : Mute or unmute
  • Q or q : End the program (exit to shell prompt)

How to find out if Advanced Power Management support available or not under Linux

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Advanced Power Management (APM) is an API developed by Intel and Microsoft, which allows BIOS to perform power management.

These days it is outdated and replaced by ACPI (The Advanced Configuration and Power Interface).

Under Linux to find out if, Advanced Power Management support available or not you need to type following commands:

$ apm_available
$ echo $?

It returns three values:

  • 0 (true) : APM subsystem is available
  • 1 (false): APM subsystem is not available
  • 2 : Usage error (arguments supplied)

You can also try out following command:

$ apm_available && echo “Yes” || echo “No APM support”

You can use following command to test whether ACPI subsystem is available or not:

$ acpi_available && echo “Yes” || echo “No APM support”

Howto: Eject cd with ssh

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Eject allows removable media (typically a CD-ROM, floppy disk, tape, or JAZ or ZIP disk) to be ejected under software control. The command can also control some multi-disc CD-ROM changers, the auto-eject feature supported by some devices, and close the disc tray of some CD-ROM drives. Eject can be used remotely over ssh session to eject cds.

First login to remote system over ssh session:
$ ssh user@ras.nixcraft.in
Eject cd using device name:
# eject /dev/cdrom
OR Eject cd using mount point
# eject /mnt/cdrom/

To close tray type command:
# eject -t /mnt/cdrom/If you have multi-disc changer then you can use eject to select disc. For example, select 4th disc on multi-disc changer:# eject -v -c4 /dev/cdrom