tk2: 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/tk2 - from package: tk2

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

Error in other languages:
tk2: bevel nie gevind nie
tk2: comandă negăsită
tk2: comando não encontrado
tk2: commande introuvable
tk2: command not found
tk2: käsku ei ole
tk2: không tìm thấy lệnh
tk2: komanda nerasta
tk2: Kommando nicht gefunden.
tk2: kommandot finns inte
tk2: komut yok
tk2: nie znaleziono polecenia
tk2: níor aimsíodh an t-ordú
tk2: no se encontró la orden
tk2: no s'ha trobat l'ordre
tk2: opdracht niet gevonden
tk2: parancs nem található
tk2: perintah tidak ditemukan
tk2: príkaz nenájdený
tk2: příkaz nenalezen
tk2: команда не найдена
tk2: командата не е открита
tk2: 命令找不到
tk2: コマンドが見つかりません