papi_version: 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/papi_version - from package: papi

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

On Debian possible default full paths are:

/usr/bin/papi_version - from package: papi-tools

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

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