pt-stalk: 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/pt-stalk - from package: percona-toolkit

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

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