pkicreate: 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/pkicreate - from package: pki-setup

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

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