newer: 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/newer - from package: texlive

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

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