jabber-roster: 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/jabber-roster - from package: jabber-roster

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

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