pbmtoicon: 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/pbmtoicon - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtoicon - from package: netpbm

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

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