h5tovtk: 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/h5tovtk - from package: h5utils

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

Error in other languages:
h5tovtk: bevel nie gevind nie
h5tovtk: comandă negăsită
h5tovtk: comando não encontrado
h5tovtk: commande introuvable
h5tovtk: command not found
h5tovtk: käsku ei ole
h5tovtk: không tìm thấy lệnh
h5tovtk: komanda nerasta
h5tovtk: Kommando nicht gefunden.
h5tovtk: kommandot finns inte
h5tovtk: komut yok
h5tovtk: nie znaleziono polecenia
h5tovtk: níor aimsíodh an t-ordú
h5tovtk: no se encontró la orden
h5tovtk: no s'ha trobat l'ordre
h5tovtk: opdracht niet gevonden
h5tovtk: parancs nem található
h5tovtk: perintah tidak ditemukan
h5tovtk: príkaz nenájdený
h5tovtk: příkaz nenalezen
h5tovtk: команда не найдена
h5tovtk: командата не е открита
h5tovtk: 命令找不到
h5tovtk: コマンドが見つかりません