rpc.idmapd: command not found

Have You tried accessing the binary with the full path?

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/rpc.idmapd - from package: nfs-utils

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

On Debian possible default full paths are:

/usr/sbin/rpc.idmapd - from package: nfs-common

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