e3: command not found

Have You tried accessing the binary with the full path?

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/e3 - from package: e3

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

On Debian possible default full paths are:

/usr/bin/e3 - from package: e3

You may install the required package with command apt-get install {package}
Error in other languages:
e3: bevel nie gevind nie
e3: comandă negăsită
e3: comando não encontrado
e3: commande introuvable
e3: command not found
e3: käsku ei ole
e3: không tìm thấy lệnh
e3: komanda nerasta
e3: Kommando nicht gefunden.
e3: kommandot finns inte
e3: komut yok
e3: nie znaleziono polecenia
e3: níor aimsíodh an t-ordú
e3: no se encontró la orden
e3: no s'ha trobat l'ordre
e3: opdracht niet gevonden
e3: parancs nem található
e3: perintah tidak ditemukan
e3: príkaz nenájdený
e3: příkaz nenalezen
e3: команда не найдена
e3: командата не е открита
e3: 命令找不到
e3: コマンドが見つかりません