makekeys: 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/makekeys - from package: cjdns

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

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