wbmptopbm: 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/wbmptopbm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/wbmptopbm - from package: netpbm

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

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