imlib-config: 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/imlib-config - from package: imlib-devel

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

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