naev: 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/naev - from package: naev

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

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