umount.ecryptfs_private: 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:

/sbin/umount.ecryptfs_private - from package: ecryptfs-utils

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

On Debian possible default full paths are:

/sbin/umount.ecryptfs_private - from package: ecryptfs-utils

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

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