tvtime: 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/tvtime - from package: tvtime

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

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