Perseus: 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/Perseus - from package: ampliconnoise

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

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