flowgrind-stop: 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/lib/debug/usr/bin/flowgrind-stop - from package: flowgrind-dbg
/usr/bin/flowgrind-stop - from package: flowgrind

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