dnssec-revoke: 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/dnssec-revoke - from package: bind

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

On Debian possible default full paths are:

/usr/sbin/dnssec-revoke - from package: bind9utils

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

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