eclipse: 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/eclipse - from package: eclipse-platform

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

On Debian possible default full paths are:

/usr/bin/eclipse - from package: eclipse-platform

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

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