ipa-replica-prepare: 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/ipa-replica-prepare - from package: ipa-server

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

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