pbmtoplot: 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/pbmtoplot - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtoplot - from package: netpbm

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

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