After several months, I have yesterday at last successfully replaced Windows 10 with Linux Mint (Cinnamon, 64-bit), and am well impressed by it as I continue to transfer my digital possessions thither from my old computer. As Avast! Antivirus is apparently unavailable for Linux, I searched briefly and found Sophos. I downloaded the installer from their official Web site, but the accompanying [instruction manual](https://secure2.sophos.com/de-de/medialibrary/PDFs/documentation/savl_9_free_sgeng.pdf?la=de-DE) (§4) specifies that one must be logged in as *root* for these purposes.

I have already tried opening the Terminal in the folder of the extracted tarball and entering *su -* ; with my password, I indeed can run programmes as root (i.e. the computer name becomes red and I see the octothorpe # in the Terminal), but even so I cannot run *install.sh* by clicking on the file and selecting *Im Terminal ausführen*; a Terminal window appears and closes in an eye-blink that the account does not have permission and thus the installation is aborted. This happens even if I open a separate Terminal window in the extracted tarball's folder (NB I used Mint's own unpacking software and not the command line specified by the manual, and extracted to a new folder in my Downloads instead of within Firefox's temporary folder) and then select *install.sh* in the same manner.

A fairly obvious method to try would be to navigate to *install.sh* within a Terminal, having previously enabled root privileges as above, and run it from there. I am still rather new to Linux and the Terminal, and do not know how to navigate within there to my Downloads folder and then to find and run *install.sh*. Another alternative would be to log in as *root* instead of as my primary account (the only one existent on the computer); there is no way to input or change the username on the login screen, so this is similarly closed off to me. How can I accomplish either of these things to install an antivirus? Either method (or any if superior) would do, but the former method strikes me as the simplest and also the most useful to learn the use of the Terminal. I thank you for your assistance.

(In case anyone suggests that antivirus for Linux is unnecessary: though I can see palpably why it is indeed so difficult for third parties to change Linux, I intend potentially to use Wine to run Windows programmes, and though Linux is obscure and secure, the additional level of protection of antivirus software, even if somewhat superfluous is certainly not a bad thing. Please also inform me whether this would better be posted in /v/linux or elsewhere.)

(A further note: I have tried other antivirus programmes, though they had their own problems. The free Comodo installer, downloaded from their official Web site, found libssl *unsatisfiable* [unerfüllbar] because I had version 1.0.0 by default whilst Comodo required version 0.9.8.; this obsoleteness is not assuring.) Clamtd from Mint's native add-on centre was two years obsolete, and I could not determine even how to download the actual version from their Web site, let alone install them.)