ecryptfs-mount-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:

/usr/bin/ecryptfs-mount-private - from package: ecryptfs-utils

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

On Debian possible default full paths are:

/usr/bin/ecryptfs-mount-private - from package: ecryptfs-utils

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

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