uhd_usrp_probe: 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/uhd_usrp_probe - from package: uhd-host

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

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