pbmtomacp: 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/pbmtomacp - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/pbmtomacp - from package: netpbm

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

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