tlock: 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 CentOS possible default full paths are:

/usr/bin/tlock - from package: tlock

You may install the required package with command yum install {package}

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