nproc: 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/nproc - from package: coreutils

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

On Debian possible default full paths are:

/usr/bin/nproc - from package: coreutils

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

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