with-lock-ex: 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/with-lock-ex - from package: chiark-utils-bin

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

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