tos-serial-debug: 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/tos-serial-debug - from package: tinyos-tools

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

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