pgmbentley: 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/pgmbentley - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmbentley - from package: netpbm

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

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