audit-viewer: 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/audit-viewer - from package: audit-viewer

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

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