zl: 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/zl - from package: zenlisp

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

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