als: 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/bin/als - from package: atool

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

On Debian possible default full paths are:

/usr/bin/als - from package: atool

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

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