makewhatis: 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/sbin/makewhatis - from package: man

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

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