hpisensor: 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/hpisensor - from package: openhpi32
/usr/bin/hpisensor - from package: openhpi

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

On Debian possible default full paths are:

/usr/bin/hpisensor - from package: openhpi-clients

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

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