curvecpmessage: 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/curvecpmessage - from package: nacl

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

On Debian possible default full paths are:

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

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

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