pbmtozinc: 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/pbmtozinc - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtozinc - from package: netpbm

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

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