pgmcrater: 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/pgmcrater - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pgmcrater - from package: netpbm

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

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