unace: 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/unace - from package: unace

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

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