ximtoppm: 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/ximtoppm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/ximtoppm - from package: netpbm

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

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