virtuoso-t: command not found

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 CentOS possible default full paths are:

/usr/bin/virtuoso-t - from package: virtuoso-opensource

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/virtuoso-t - from package: virtuoso-opensource-6.1-bin

You may install the required package with command apt-get install {package}

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