From Newsgroup: alt.os.linux.ubuntu

Hi all,
I've been using linux (Ubuntu/Mint mainly) for 20 years and I still find things that I don't understand. I need some help!

I have a need to run the following code after generating a virtual
machine in LXD. The following code runs fine in the VM from the terminal:
sudo su -
mount -t 9p config /mnt
cd /mnt
./install.sh
exit

However, when I converted the commands to my bash script and try to run
this code , it fails:
cd /mnt
sudo mount -t 9p config /mnt
sudo /mnt/install.sh
.
.

The error it gives me is:
"This script must be run from within the 9p mount"

Can someone explain how I can accomplish the intent of this code?
Richard


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From Newsgroup: alt.os.linux.ubuntu

On 2025-07-08, rsutton wrote:

Hi all,
The following code runs fine in the VM from the terminal:
sudo su -
mount -t 9p config /mnt
cd /mnt
./install.sh
exit

However, when I converted the commands to my bash script and try to run
this code , it fails:
cd /mnt
sudo mount -t 9p config /mnt
sudo /mnt/install.sh

The error it gives me is:
"This script must be run from within the 9p mount"

Can someone explain how I can accomplish the intent of this code?

Well, in the working code, your current working directory is the one
that contains the install script; whereas the non-working code, you are
calling the explicit path (which sort of implies you are "somewhere
else").

Chances are the script does a bunch of things relative to the current
working directory, and it performs a check to ensure that its execution
path is also the current working directory.
--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860
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From Newsgroup: alt.os.linux.ubuntu

rsutton <rsutton43@comcast.net> writes:

Hi all,
I've been using linux (Ubuntu/Mint mainly) for 20 years and I still
find things that I don't understand. I need some help!

I have a need to run the following code after generating a virtual
machine in LXD. The following code runs fine in the VM from the
terminal:
sudo su -
mount -t 9p config /mnt
cd /mnt
./install.sh
exit

However, when I converted the commands to my bash script and try to
run this code , it fails:
cd /mnt

After this your current working directory is the /mnt directory in the
root filesystem.

sudo mount -t 9p config /mnt

After the mount command, the path /mnt refers to the root of the 9p
filesystem (whatever that is). But your current working directory
remains the (now hidden) /mnt directory of the root filesystem.

So the answer is to move the ‘cd’ command in your script one line down.

sudo /mnt/install.sh
.
.

The error it gives me is:
"This script must be run from within the 9p mount"

--
https://www.greenend.org.uk/rjk/
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From Newsgroup: alt.os.linux.ubuntu

Richard Kettlewell wrote:

rsutton <rsutton43@comcast.net> writes:

Hi all,
I've been using linux (Ubuntu/Mint mainly) for 20 years and I still
find things that I don't understand. I need some help!

I have a need to run the following code after generating a virtual
machine in LXD. The following code runs fine in the VM from the
terminal:
sudo su -
mount -t 9p config /mnt
cd /mnt
./install.sh
exit

However, when I converted the commands to my bash script and try to
run this code , it fails:
cd /mnt

After this your current working directory is the /mnt directory in the
root filesystem.

sudo mount -t 9p config /mnt

After the mount command, the path /mnt refers to the root of the 9p filesystem (whatever that is). But your current working directory
remains the (now hidden) /mnt directory of the root filesystem.

So the answer is to move the ‘cd’ command in your script one line down.

sudo /mnt/install.sh
.
.

The error it gives me is:
"This script must be run from within the 9p mount"

To further expand on what Richard here said, the hint was in the
differences in OP's original post. When he did it step by step by
command line he cd into mounted dir before running install.sh whereas hi
script did not.

The install.sh script must reference assets within the same directory as
the script AND the script assumes the pwd is that directory.

If you are the author of install.sh, what I do to prevent this problem
in my scripts:

SCRIPT_PATH="$(dirname "$(realpath "$0")")"
# reference some asset located with this script
source "$SCRIPT_PATH/some_asset"
# or alternatively cd to script directory first
cd $SCRIPT_PATH"
source ./some_other_asset
--
Take care,

Jonathan
-------------------
LITTLE WORKS STUDIO
http://www.LittleWorksStudio.com
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