tos-serial-configure: 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-configure - from package: tinyos-tools

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

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