GNU/
        On certain 
        Retrieve your distribution name (e.g. 
lsb_release -cs 
Download the TeXmacs public key (into the auxiliary file apt-texmacs.asc):
curl --insecure https://ftp.texmacs.org/TeXmacs/tmftp/repos/apt/apt-texmacs.asc --output apt-texmacs.asc 
Obtain root privileges:
sudo bash 
        Import the key in the 
apt-key add apt-texmacs.asc 
Remove the temporary key file:
rm apt-texmacs.asc 
Add the texmacs repository in
add-apt-repository "deb http://ftp.texmacs.org/TeXmacs/tmftp/repos/apt/ stretch universe" 
Update the package list:
apt-get update 
Install TeXmacs:
apt-get install texmacs 
Return to your regular account:
exit 
        Retrieve your distribution name (e.g. 
lsb_release -cs 
Download the TeXmacs public key (into the auxiliary file apt-texmacs.asc):
curl --insecure https://ftp.texmacs.org/TeXmacs/tmftp/repos/apt/apt-texmacs.asc --output apt-texmacs.asc 
Obtain root privileges:
sudo bash 
        Import the key in the 
apt-key add apt-texmacs.asc 
Remove the temporary key file:
rm apt-texmacs.asc 
Add the texmacs repository in
add-apt-repository "deb http://ftp.texmacs.org/TeXmacs/tmftp/repos/apt/ yakkety universe" 
Update the package list:
apt-get update 
Install TeXmacs:
apt-get install texmacs 
Return to your regular account:
exit