amaddclient: 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 CentOS possible default full paths are:

/usr/sbin/amaddclient - from package: amanda-server

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/amaddclient - from package: amanda-common

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

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