dotlock: 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/dotlock - from package: mailavenger

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

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