combine: 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/combine - from package: moreutils

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

On Debian possible default full paths are:

/usr/bin/combine - from package: moreutils

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

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