pinentry-qt4: 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/pinentry-qt4 - from package: pinentry-qt4

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

On Debian possible default full paths are:

/usr/bin/pinentry-qt4 - from package: pinentry-qt4

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

Error in other languages:
pinentry-qt4: bevel nie gevind nie
pinentry-qt4: comandă negăsită
pinentry-qt4: comando não encontrado
pinentry-qt4: commande introuvable
pinentry-qt4: command not found
pinentry-qt4: käsku ei ole
pinentry-qt4: không tìm thấy lệnh
pinentry-qt4: komanda nerasta
pinentry-qt4: Kommando nicht gefunden.
pinentry-qt4: kommandot finns inte
pinentry-qt4: komut yok
pinentry-qt4: nie znaleziono polecenia
pinentry-qt4: níor aimsíodh an t-ordú
pinentry-qt4: no se encontró la orden
pinentry-qt4: no s'ha trobat l'ordre
pinentry-qt4: opdracht niet gevonden
pinentry-qt4: parancs nem található
pinentry-qt4: perintah tidak ditemukan
pinentry-qt4: príkaz nenájdený
pinentry-qt4: příkaz nenalezen
pinentry-qt4: команда не найдена
pinentry-qt4: командата не е открита
pinentry-qt4: 命令找不到
pinentry-qt4: コマンドが見つかりません