readahead-collector: 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:

/sbin/readahead-collector - from package: readahead

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

On Debian possible default full paths are:

/sbin/readahead-collector - from package: readahead-fedora

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

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