papi_mem_info: 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_mem_info - from package: papi

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

On Debian possible default full paths are:

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

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

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