amarchiver: 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/amarchiver - from package: amanda

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

On Debian possible default full paths are:

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

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

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