reposync: 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/reposync - from package: yum-utils

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

On Debian possible default full paths are:

/usr/bin/reposync - from package: yum-utils

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

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