openvasclient-mkcert: 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/openvasclient-mkcert - from package: openvas-client

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

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