s3qllock: 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/s3qllock - from package: s3ql

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

Error in other languages:
s3qllock: bevel nie gevind nie
s3qllock: comandă negăsită
s3qllock: comando não encontrado
s3qllock: commande introuvable
s3qllock: command not found
s3qllock: käsku ei ole
s3qllock: không tìm thấy lệnh
s3qllock: komanda nerasta
s3qllock: Kommando nicht gefunden.
s3qllock: kommandot finns inte
s3qllock: komut yok
s3qllock: nie znaleziono polecenia
s3qllock: níor aimsíodh an t-ordú
s3qllock: no se encontró la orden
s3qllock: no s'ha trobat l'ordre
s3qllock: opdracht niet gevonden
s3qllock: parancs nem található
s3qllock: perintah tidak ditemukan
s3qllock: príkaz nenájdený
s3qllock: příkaz nenalezen
s3qllock: команда не найдена
s3qllock: командата не е открита
s3qllock: 命令找不到
s3qllock: コマンドが見つかりません