mn10300-linux-gnu-size: 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/mn10300-linux-gnu-size - from package: binutils-mn10300-linux-gnu

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

Error in other languages:
mn10300-linux-gnu-size: bevel nie gevind nie
mn10300-linux-gnu-size: comandă negăsită
mn10300-linux-gnu-size: comando não encontrado
mn10300-linux-gnu-size: commande introuvable
mn10300-linux-gnu-size: command not found
mn10300-linux-gnu-size: käsku ei ole
mn10300-linux-gnu-size: không tìm thấy lệnh
mn10300-linux-gnu-size: komanda nerasta
mn10300-linux-gnu-size: Kommando nicht gefunden.
mn10300-linux-gnu-size: kommandot finns inte
mn10300-linux-gnu-size: komut yok
mn10300-linux-gnu-size: nie znaleziono polecenia
mn10300-linux-gnu-size: níor aimsíodh an t-ordú
mn10300-linux-gnu-size: no se encontró la orden
mn10300-linux-gnu-size: no s'ha trobat l'ordre
mn10300-linux-gnu-size: opdracht niet gevonden
mn10300-linux-gnu-size: parancs nem található
mn10300-linux-gnu-size: perintah tidak ditemukan
mn10300-linux-gnu-size: príkaz nenájdený
mn10300-linux-gnu-size: příkaz nenalezen
mn10300-linux-gnu-size: команда не найдена
mn10300-linux-gnu-size: командата не е открита
mn10300-linux-gnu-size: 命令找不到
mn10300-linux-gnu-size: コマンドが見つかりません