ipmi-sensors: 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/ipmi-sensors - from package: freeipmi

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

On Debian possible default full paths are:

/usr/sbin/ipmi-sensors - from package: freeipmi-tools

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

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