prove.pir: 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/lib64/parrot/3.3.0/bin/prove.pir - from package: parrot
/usr/lib/parrot/3.3.0/bin/prove.pir - from package: parrot

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

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