ent: 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/ent - from package: ent

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

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