papi_decode: 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_decode - from package: papi

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

On Debian possible default full paths are:

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

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

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