ipa-join: 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-join - from package: ipa-client

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

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