rake-compiler: 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/rake-compiler - from package: rubygem-rake-compiler
/usr/lib/ruby/gems/1.8/gems/rake-compiler-0.9.3/bin/rake-compiler - from package: rubygem-rake-compiler

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

On Debian possible default full paths are:

/usr/bin/rake-compiler - from package: rake-compiler

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

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