smbios-lcd-brightness: 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/smbios-lcd-brightness - from package: smbios-utils-python

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

On Debian possible default full paths are:

/usr/sbin/smbios-lcd-brightness - from package: smbios-utils

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

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