applypatch: 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/applypatch - from package: makepatch

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

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