banner: 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/banner - from package: banner

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

On Debian possible default full paths are:

/usr/bin/banner - from package: afterstep
/usr/bin/banner - from package: sysvbanner

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

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