pitivi: command not found

Have You tried accessing the binary with the full path?

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/pitivi - from package: pitivi

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