pigz: 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/pigz - from package: pigz

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

On Debian possible default full paths are:

/usr/bin/pigz - from package: pigz

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

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