olpc-volume: 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 Debian possible default full paths are:

/usr/bin/olpc-volume - from package: olpc-kbdshim

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

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