systemd-detect-virt: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/systemd-detect-virt - from package: systemd

You may install the required package with command apt-get install {package}
Error in other languages:
systemd-detect-virt: bevel nie gevind nie
systemd-detect-virt: comandă negăsită
systemd-detect-virt: comando não encontrado
systemd-detect-virt: commande introuvable
systemd-detect-virt: command not found
systemd-detect-virt: käsku ei ole
systemd-detect-virt: không tìm thấy lệnh
systemd-detect-virt: komanda nerasta
systemd-detect-virt: Kommando nicht gefunden.
systemd-detect-virt: kommandot finns inte
systemd-detect-virt: komut yok
systemd-detect-virt: nie znaleziono polecenia
systemd-detect-virt: níor aimsíodh an t-ordú
systemd-detect-virt: no se encontró la orden
systemd-detect-virt: no s'ha trobat l'ordre
systemd-detect-virt: opdracht niet gevonden
systemd-detect-virt: parancs nem található
systemd-detect-virt: perintah tidak ditemukan
systemd-detect-virt: príkaz nenájdený
systemd-detect-virt: příkaz nenalezen
systemd-detect-virt: команда не найдена
systemd-detect-virt: командата не е открита
systemd-detect-virt: 命令找不到
systemd-detect-virt: コマンドが見つかりません