viewmount: 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/bin/viewmount - from package: umview

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

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