mockchain: 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/mockchain - from package: mock

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

On Debian possible default full paths are:

/usr/bin/mockchain - from package: mock

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

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