stm32flash: 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/stm32flash - from package: stm32flash

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

Error in other languages:
stm32flash: bevel nie gevind nie
stm32flash: comandă negăsită
stm32flash: comando não encontrado
stm32flash: commande introuvable
stm32flash: command not found
stm32flash: käsku ei ole
stm32flash: không tìm thấy lệnh
stm32flash: komanda nerasta
stm32flash: Kommando nicht gefunden.
stm32flash: kommandot finns inte
stm32flash: komut yok
stm32flash: nie znaleziono polecenia
stm32flash: níor aimsíodh an t-ordú
stm32flash: no se encontró la orden
stm32flash: no s'ha trobat l'ordre
stm32flash: opdracht niet gevonden
stm32flash: parancs nem található
stm32flash: perintah tidak ditemukan
stm32flash: príkaz nenájdený
stm32flash: příkaz nenalezen
stm32flash: команда не найдена
stm32flash: командата не е открита
stm32flash: 命令找不到
stm32flash: コマンドが見つかりません