egrep: 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:

/bin/egrep - from package: grep

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

On Debian possible default full paths are:

/bin/egrep - from package: grep

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

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