txt2gcal: 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/txt2gcal - from package: gcal

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

Error in other languages:
txt2gcal: bevel nie gevind nie
txt2gcal: comandă negăsită
txt2gcal: comando não encontrado
txt2gcal: commande introuvable
txt2gcal: command not found
txt2gcal: käsku ei ole
txt2gcal: không tìm thấy lệnh
txt2gcal: komanda nerasta
txt2gcal: Kommando nicht gefunden.
txt2gcal: kommandot finns inte
txt2gcal: komut yok
txt2gcal: nie znaleziono polecenia
txt2gcal: níor aimsíodh an t-ordú
txt2gcal: no se encontró la orden
txt2gcal: no s'ha trobat l'ordre
txt2gcal: opdracht niet gevonden
txt2gcal: parancs nem található
txt2gcal: perintah tidak ditemukan
txt2gcal: príkaz nenájdený
txt2gcal: příkaz nenalezen
txt2gcal: команда не найдена
txt2gcal: командата не е открита
txt2gcal: 命令找不到
txt2gcal: コマンドが見つかりません