brushtopbm: 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/brushtopbm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/brushtopbm - from package: netpbm

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

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