buffer: 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/buffer - from package: buffer

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

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