uname: 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:

/bin/uname - from package: coreutils

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

On Debian possible default full paths are:

/bin/uname - from package: coreutils
/usr/lib/klibc/bin/uname - from package: klibc-utils

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

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