isqlw-vt: 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/isqlw-vt - from package: virtuoso-opensource-utils

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

On Debian possible default full paths are:

/usr/bin/isqlw-vt - from package: virtuoso-opensource-6.1-bin

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

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