avr-size: command not found

Have You tried accessing the binary with the full path?

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/avr-size - from package: avr-binutils

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

On Debian possible default full paths are:

/usr/bin/avr-size - from package: binutils-avr

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