mergelib: 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/mergelib - from package: imake

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

On Debian possible default full paths are:

/usr/bin/mergelib - from package: xutils-dev

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

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