pampop9: 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/pampop9 - from package: netpbm-progs

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

Error in other languages:
pampop9: bevel nie gevind nie
pampop9: comandă negăsită
pampop9: comando não encontrado
pampop9: commande introuvable
pampop9: command not found
pampop9: käsku ei ole
pampop9: không tìm thấy lệnh
pampop9: komanda nerasta
pampop9: Kommando nicht gefunden.
pampop9: kommandot finns inte
pampop9: komut yok
pampop9: nie znaleziono polecenia
pampop9: níor aimsíodh an t-ordú
pampop9: no se encontró la orden
pampop9: no s'ha trobat l'ordre
pampop9: opdracht niet gevonden
pampop9: parancs nem található
pampop9: perintah tidak ditemukan
pampop9: príkaz nenájdený
pampop9: příkaz nenalezen
pampop9: команда не найдена
pampop9: командата не е открита
pampop9: 命令找不到
pampop9: コマンドが見つかりません