airspy_info: 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

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/airspy_info - from package: airspy

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