pgmramp: 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/pgmramp - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmramp - from package: netpbm

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

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