autoreconf: 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/autoreconf - from package: autoconf

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

On Debian possible default full paths are:

/usr/bin/autoreconf - from package: autoconf2.13
/usr/bin/autoreconf - from package: autoconf

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

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