pbmto4425: 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/pbmto4425 - from package: netpbm-progs

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

Error in other languages:
pbmto4425: bevel nie gevind nie
pbmto4425: comandă negăsită
pbmto4425: comando não encontrado
pbmto4425: commande introuvable
pbmto4425: command not found
pbmto4425: käsku ei ole
pbmto4425: không tìm thấy lệnh
pbmto4425: komanda nerasta
pbmto4425: Kommando nicht gefunden.
pbmto4425: kommandot finns inte
pbmto4425: komut yok
pbmto4425: nie znaleziono polecenia
pbmto4425: níor aimsíodh an t-ordú
pbmto4425: no se encontró la orden
pbmto4425: no s'ha trobat l'ordre
pbmto4425: opdracht niet gevonden
pbmto4425: parancs nem található
pbmto4425: perintah tidak ditemukan
pbmto4425: príkaz nenájdený
pbmto4425: příkaz nenalezen
pbmto4425: команда не найдена
pbmto4425: командата не е открита
pbmto4425: 命令找不到
pbmto4425: コマンドが見つかりません