can not edit /etc/default/grub

[oldfogie]

I have an old laptop that dual boots windows 7 and Linux Mint 19 Cinnamon
I'm trying to change the grub default.

I've tried sudo grub-set-default - didnt work

I've tried editing /etc/default/grub as sudo nano /etc/default/grub or sudo vi /etc/default/grub
and the file is displayed but I cant make changes

in /etc/default/grub ls-l shows the permissions as -rw-r--r--

help please?

[Pjotr]

Try this:

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xed admin:///etc/default/grub

The multiple slashes are no typo. Use copy/paste in order to ensure that the command is being transferred correctly.

If you wish to make Windows the default boot, this is how:
https://easylinuxtipsproject.blogspot.c ... 1.html#ID1
(item 1)

[sebastjava]

After you succeeded in editing and saving etc/default/grub, you must run this:

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sudo update-grub

You want to change the default starting OS ?
Also, this might be a bit off-topic, but if you are talking about the default starting OS, i found it very useful to make it start with your last chosen OS. This way, I usually automatically get it started or restarted on Mint, but when I go into Windows, which rarely happens, then there are tons of updates, and many required restart, restart, and restart again. So, with my custom settings, when Windows needs to restart to complete some update, it does so, automatically.

I found this tweak from there: https://askubuntu.com/questions/148662/ ... ast-choice

Put the following in /etc/default/grub (command line: xed admin:///etc/default/grub):

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GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true

Do some find/replace: those parameters are probably already there, so you need to edit them, not adding new lines.

Save this file and then run:

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sudo update-grub

[Flemur]

I've tried sudo grub-set-default - didnt work

Rather than tell what didn't happen, what DID happen when you ran sudo grub-set-default?

I've tried editing /etc/default/grub as sudo nano /etc/default/grub or sudo vi /etc/default/grub
and the file is displayed but I cant make changes

Again, what happened?

Either of those should work; try sudo vi /etc/default/grub then type an 'a', then type some other characters; they should be added after the initial # in the file. Then type the ESCAPE character to get out of insert mode. If you want to save it (the change you'd make from doing what I described will just change the comment, won't affect any settings), type :w.

Edit: type :q! to exit changed file without saving, or just :q to exit after saving.

[ricardogroetaers]

How difficult is it to open, as root, the "/etc/default/" folder with File Manager and open the "grub" file with a simple Text Editor (Xed for example) and edit the file?
Don't complicate things!

Note: The changes you make to this file are your responsibility.

[mikeflan]

The changes you make to this file are your responsibility.

This is a good point. I highly recommend backing up fstab before modifying it:

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sudo cp /etc/fstab /etc/fstab.bak

It should produce no output. That means it worked. You could need that bak file later

[karlchen]

What is the point in creating a backup copy of the file /etc/fstab, although the topic of this thread is editing the file /etc/default/grub? - Minor confusion.

[sebastjava]

[...] This is a good point. I highly recommend backing up fstab before modifying it [...]

fstab ? Why ? Please read the two first lines on /etc/default/grub:
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.

So, the file you are modifying is /boot/grub/grub.cfg. But don't touch this file directly ! Do as said before: edit /etc/default/grub and then run sudo update-grub for those changes to be made. And, yes, it would be a good idea to backup this /boot/grub/grub.cfg before doing anything.

[Flemur]

What is the point in creating a backup copy of the file /etc/fstab, although the topic of this thread is editing the file /etc/default/grub? - Minor confusion.

He probably meant sudo cp /etc/default/grub /etc/default/grub.bak which is a good idea, especially for someone not familiar with the text editors.

[sebastjava]

In the event of a major disaster

Let's suppose you got confused and did some really bad mistake. That is just an unlikely possibility. Murphy's law. Well, in the event of a major disaster, you could always restart from a USB key or CD with a live Mint installer, and then replace this /boot/grub/grub.cfg with your backup copy.

To be done as a last resort only.

[Flemur]

replace this /boot/grub/grub.cfg with the one from your USB key.

I'm pretty sure that wouldn't work. I don't have a Mint installer handy, but the Ubuntu 18.x one boots everything from /casper rather than /boot.

The thing to do is make backups on the installed OS of everything you're going to change (e.g. just cp X X.bak, as mentioned above, before you edit file X) then if you can't boot the OS, boot the installer, go to the broken OS and cp X.bak X to restore from the un-edited file. (Personally I'd never bother - which is why I didn't think of it - because I have a full backup of the OS that I can use to restore any OS file).

[sebastjava]

[...] I'm pretty sure that wouldn't work. [...]

Okay. I re-edited my preceding post accordingly: use a backup copy.

[mikeflan]

And I had a senior moment with that fstab backup. It is a good idea, but unrelated to this thread.

[Aztaroth]

Any Timeshift snap also keeps copy/backup of all system files. A snap can be restored with the Timeshift app but it can also be read as a 'normal' directory.
In each snap directory (named after the date it has been created), there is a localhost subdirectory containing all system files in the same locations (/bin, /boot, /etc...) than the running system. A single file (grub, fstab, cron...) can be manually restored if necessary.