ttv: 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 CentOS possible default full paths are:

/usr/bin/ttv - from package: xawtv

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/ttv - from package: ttv

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

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