oracle: 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/oracle - from package: golang-googlecode-tools-oracle

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

On Debian possible default full paths are:

/usr/bin/oracle - from package: golang-go.tools

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

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