prj2make: 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/prj2make - from package: mono-devel

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

Error in other languages:
prj2make: bevel nie gevind nie
prj2make: comandă negăsită
prj2make: comando não encontrado
prj2make: commande introuvable
prj2make: command not found
prj2make: käsku ei ole
prj2make: không tìm thấy lệnh
prj2make: komanda nerasta
prj2make: Kommando nicht gefunden.
prj2make: kommandot finns inte
prj2make: komut yok
prj2make: nie znaleziono polecenia
prj2make: níor aimsíodh an t-ordú
prj2make: no se encontró la orden
prj2make: no s'ha trobat l'ordre
prj2make: opdracht niet gevonden
prj2make: parancs nem található
prj2make: perintah tidak ditemukan
prj2make: príkaz nenájdený
prj2make: příkaz nenalezen
prj2make: команда не найдена
prj2make: командата не е открита
prj2make: 命令找不到
prj2make: コマンドが見つかりません