winicontoppm: 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/winicontoppm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/winicontoppm - from package: netpbm

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

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