darts: 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/darts - from package: darts

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

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