pnmenlarge: 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/pnmenlarge - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pnmenlarge - from package: netpbm

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

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