upx-ucl: 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/upx-ucl - from package: upx-ucl

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

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