freefoam-foamToVTK: 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/freefoam-foamToVTK - from package: freefoam

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

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