ipmi_ui: 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/ipmi_ui - from package: OpenIPMI

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

On Debian possible default full paths are:

/usr/bin/ipmi_ui - from package: OpenIPMI

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

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