selfsign-getcert: 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/selfsign-getcert - from package: certmonger

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

On Debian possible default full paths are:

/usr/bin/selfsign-getcert - from package: certmonger

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

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