s3: 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/s3 - from package: libs3

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

On Debian possible default full paths are:

/usr/bin/s3 - from package: libs3-2

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

Error in other languages:
s3: bevel nie gevind nie
s3: comandă negăsită
s3: comando não encontrado
s3: commande introuvable
s3: command not found
s3: käsku ei ole
s3: không tìm thấy lệnh
s3: komanda nerasta
s3: Kommando nicht gefunden.
s3: kommandot finns inte
s3: komut yok
s3: nie znaleziono polecenia
s3: níor aimsíodh an t-ordú
s3: no se encontró la orden
s3: no s'ha trobat l'ordre
s3: opdracht niet gevonden
s3: parancs nem található
s3: perintah tidak ditemukan
s3: príkaz nenájdený
s3: příkaz nenalezen
s3: команда не найдена
s3: командата не е открита
s3: 命令找不到
s3: コマンドが見つかりません