mirrorMappings: 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/mirrorMappings - from package: perl-Unicode-Map

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

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