lemon: 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/lemon - from package: lemon

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

On Debian possible default full paths are:

/usr/bin/lemon - from package: lemon

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

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