updatedb.sh: 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/share/roundcubemail/bin/updatedb.sh - from package: roundcubemail

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

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