sputoppm: 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/sputoppm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/sputoppm - from package: netpbm

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

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