ppmdraw: 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/ppmdraw - from package: netpbm-progs

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

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