asciitopgm: 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/asciitopgm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/asciitopgm - from package: netpbm

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

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