proofexecv: 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/proofexecv - from package: root-xproof

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

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