zarafa-ical: 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/zarafa-ical - from package: zarafa-ical

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

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