sbigtopgm: 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/sbigtopgm - from package: netpbm-progs

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

On Debian possible default full paths are:

/usr/bin/sbigtopgm - from package: netpbm

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

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