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 CentOS possible default full paths are:

/usr/sbin/iso8601 - from package: pacemaker-cli

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

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