saga_cmd: 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_cmd - from package: saga

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

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