pbmminkowski: 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/pbmminkowski - from package: netpbm-progs

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

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