ical2html: 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/ical2html - from package: ical2html

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

Error in other languages:
ical2html: bevel nie gevind nie
ical2html: comandă negăsită
ical2html: comando não encontrado
ical2html: commande introuvable
ical2html: command not found
ical2html: käsku ei ole
ical2html: không tìm thấy lệnh
ical2html: komanda nerasta
ical2html: Kommando nicht gefunden.
ical2html: kommandot finns inte
ical2html: komut yok
ical2html: nie znaleziono polecenia
ical2html: níor aimsíodh an t-ordú
ical2html: no se encontró la orden
ical2html: no s'ha trobat l'ordre
ical2html: opdracht niet gevonden
ical2html: parancs nem található
ical2html: perintah tidak ditemukan
ical2html: príkaz nenájdený
ical2html: příkaz nenalezen
ical2html: команда не найдена
ical2html: командата не е открита
ical2html: 命令找不到
ical2html: コマンドが見つかりません