acl2: 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/bin/acl2 - from package: acl2

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

Error in other languages:
acl2: bevel nie gevind nie
acl2: comandă negăsită
acl2: comando não encontrado
acl2: commande introuvable
acl2: command not found
acl2: käsku ei ole
acl2: không tìm thấy lệnh
acl2: komanda nerasta
acl2: Kommando nicht gefunden.
acl2: kommandot finns inte
acl2: komut yok
acl2: nie znaleziono polecenia
acl2: níor aimsíodh an t-ordú
acl2: no se encontró la orden
acl2: no s'ha trobat l'ordre
acl2: opdracht niet gevonden
acl2: parancs nem található
acl2: perintah tidak ditemukan
acl2: príkaz nenájdený
acl2: příkaz nenalezen
acl2: команда не найдена
acl2: командата не е открита
acl2: 命令找不到
acl2: コマンドが見つかりません