ovs-dpctl: 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/ovs-dpctl - from package: openvswitch-switch

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