papi_cost: 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_cost - from package: papi

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

On Debian possible default full paths are:

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

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

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