pgmnorm: 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/pgmnorm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmnorm - from package: netpbm

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

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