gdeskcal: 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/gdeskcal - from package: gdeskcal

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

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