ff-get-dep: 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/ff-get-dep - from package: freefem++

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

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