cmuwmtopbm: 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/cmuwmtopbm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/cmuwmtopbm - from package: netpbm

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

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