pilot-read-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/pilot-read-ical - from package: pilot-link

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

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