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I have the same problem as found on this link

Screen turns black after booting, backlight only works in recovery mode on an Acer Aspire 5736z

I've never used any Linux before so if someone could tell me exactly step-by-step what to do with the answer given by "ashutosh". Thanks

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Step by step

Open the Terminal application and copy/paste the following command in the window that opens (called a terminal or console) and press Enter:

sudo sed -i 's/GRUB_CMDLINE_LINUX=""/GRUB_CMDLINE_LINUX="acpi_osi=Linux"/g' /etc/default/grub

You'll be prompted for a password. Enter your Ubuntu password, followed by Enter.

  • Note that your key-presses will not show up as asterisks or anything else while you are typing your password; this is a security feature and is normal.

What we're doing here

  • Prefixing a command with sudo runs it with administrative (or, in Unix terminology, root) privileges.

  • sed is the Unix command-line string editor.

  • The -i option makes sed edit files in-place instead of simply showing you what would be changed but not actually saving the changes.

  • The 's/GRUB_CMDLINE_LINUX=""/GRUB_CMDLINE_LINUX="acpi_osi=Linux"/g' part is what does the search and replace.

  • /etc/default/grub is the file to edit. It's a configuration file for Grub, Ubuntu's bootloader (the program that loads Ubuntu when you turn on your computer).

Update Grub with the changes

Run this command:

sudo update-grub

This makes Grub see the changes in its configuration file and apply the new config.

Try it out

Reboot your computer to test out the change you made. If it works, you're good to go, and you've successfully edited you're first file using the command line!

Congratulations :)

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How can add these codes when I can't see what's on the laptop screen even with a flashlight – Mysterio Aug 9 '13 at 9:31

A better solution for me was to turn on the laptop backlight with an entry in /etc/rc.local -- see

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If the commands that SirCharlo gave you don't work, when Ubuntu starts up try pressing the button(s) that dim or brighten the display of your laptop. It should work after that, at least on an acer aspire 5736z.

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