amcheck: 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/amcheck - from package: amanda-server

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

On Debian possible default full paths are:

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

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

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