bmptoppm: 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/bmptoppm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/bmptoppm - from package: netpbm

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

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