newgem.tt: 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/lib/ruby/gems/1.8/gems/bundler-1.5.2/lib/bundler/templates/newgem/bin/newgem.tt - from package: rubygem-bundler

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

On Debian possible default full paths are:

/usr/lib/ruby/vendor_ruby/bundler/templates/newgem/bin/newgem.tt - from package: bundler

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

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