juyin-learn: 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 Debian possible default full paths are:

/usr/bin/juyin-learn - from package: gcin

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

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