manpath: 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/manpath - from package: man

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

On Debian possible default full paths are:

/usr/bin/manpath - from package: man-db

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

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