curvecpmakekey: 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/curvecpmakekey - from package: nacl

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

On Debian possible default full paths are:

/usr/bin/curvecpmakekey - from package: nacl-tools

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

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