expire-iso8601: 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/expire-iso8601 - from package: chiark-scripts

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

Error in other languages:
expire-iso8601: bevel nie gevind nie
expire-iso8601: comandă negăsită
expire-iso8601: comando não encontrado
expire-iso8601: commande introuvable
expire-iso8601: command not found
expire-iso8601: käsku ei ole
expire-iso8601: không tìm thấy lệnh
expire-iso8601: komanda nerasta
expire-iso8601: Kommando nicht gefunden.
expire-iso8601: kommandot finns inte
expire-iso8601: komut yok
expire-iso8601: nie znaleziono polecenia
expire-iso8601: níor aimsíodh an t-ordú
expire-iso8601: no se encontró la orden
expire-iso8601: no s'ha trobat l'ordre
expire-iso8601: opdracht niet gevonden
expire-iso8601: parancs nem található
expire-iso8601: perintah tidak ditemukan
expire-iso8601: príkaz nenájdený
expire-iso8601: příkaz nenalezen
expire-iso8601: команда не найдена
expire-iso8601: командата не е открита
expire-iso8601: 命令找不到
expire-iso8601: コマンドが見つかりません