pnmnoraw: 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/pnmnoraw - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pnmnoraw - from package: netpbm

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

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