ul: 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/ul - from package: util-linux-ng

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

On Debian possible default full paths are:

/usr/bin/ul - from package: adun.app
/usr/bin/ul - from package: bsdmainutils

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

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