amdump_client: 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/sbin/amdump_client - from package: amanda-common

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

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