motion: 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/motion - from package: motion

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

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