tlsdate: 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/tlsdate - from package: tlsdate

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

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