How to install Software via SSH

Hello,

I just installed LibreELEC 9.2.3 (Kodi V 18.7) on my Raspberry Pi 3 b+.

To power up the Pi I want to use this switch from PiSupply because I dont want to unplug and plug again the usb power cable. With this switch I just have to push a button on the case to boot/power down LibreELEC.

But this switch needs software to work propperly. I tried to install it using SSH because it seems like there is no terminal avaiable in LibreELEC. UnfortunalIy get the following error:

##############################################
#                 LibreELEC                  #
#            https://libreelec.tv            #
##############################################

LibreELEC (official): 9.2.3 (RPi2.arm)
LibreELEC-SSH:~ # curl -sSL https://pisupp.ly/piswitchcode | bash

 There is no working 'apt-get'.

 'apt-get' is a command to install, update and remove software which
 is stored in a non local repo. 'apt-get' does nothing then connecting to such
 repo, downloads the software, unpacks the software, updates a big
 local database with all filepaths and other informations about the
 installed software or removes or updates installed Software.

 With LibreELEC it is not possible to change the system for security and
 stability reasons so even 'apt-get' would not be able to do this.
 We also dont have and want to maintain such a repo for various other
 great reasons.

 Also Ubuntu or Debian packages are often outdated and not compatible
 with LibreELEC

 TIP: use Kodi's addon browser to enhance your LibreELEC system
bash: git: not found
mkdir: can't create directory '/opt/piswitch': Read-only file system
cp: can't stat 'Pi-Supply-Switch/softshut.py': No such file or directory
bash: whiptail: not found

I removed "sudo" from the command because I am already root when I use SSH.

So I cannot install the software using curl -sSL. Is there any other way installing the software? I don´t know if I can just use another commant instead of curls -sSL or apt-get (even though I didn´t used apt-get, it is listet in the error log) or if I can edit some files on the SD Card (I am really new to both linux and libreELEC). Or can I install the software using the addons in Kodi?

In case there is no way installing the software, are there any other ways to boot the RasPi with a button? I know, a switch would be much easier, but I dont want to flip it anytime I powered off the system to cut the power circuit.

Thank you for your help

Thank you very much for your response. I am going to try this out!

Thank you again for your help. It worked! Unfortunaly the Pi switches off within 2 minutes, but thats a known issue. I am going to try the workaround provided by Pi Supply.