saga-depends: 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/saga-depends - from package: libsaga-dev

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

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