pgmoil: 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/pgmoil - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmoil - from package: netpbm

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

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