i-viewdb: 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 Debian possible default full paths are:

/usr/sbin/i-viewdb - from package: integrit

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

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