kbuildsycoca4: 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/kbuildsycoca4 - from package: kdelibs

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

On Debian possible default full paths are:

/usr/bin/kbuildsycoca4 - from package: kdelibs-bin

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

Error in other languages:
kbuildsycoca4: bevel nie gevind nie
kbuildsycoca4: comandă negăsită
kbuildsycoca4: comando não encontrado
kbuildsycoca4: commande introuvable
kbuildsycoca4: command not found
kbuildsycoca4: käsku ei ole
kbuildsycoca4: không tìm thấy lệnh
kbuildsycoca4: komanda nerasta
kbuildsycoca4: Kommando nicht gefunden.
kbuildsycoca4: kommandot finns inte
kbuildsycoca4: komut yok
kbuildsycoca4: nie znaleziono polecenia
kbuildsycoca4: níor aimsíodh an t-ordú
kbuildsycoca4: no se encontró la orden
kbuildsycoca4: no s'ha trobat l'ordre
kbuildsycoca4: opdracht niet gevonden
kbuildsycoca4: parancs nem található
kbuildsycoca4: perintah tidak ditemukan
kbuildsycoca4: príkaz nenájdený
kbuildsycoca4: příkaz nenalezen
kbuildsycoca4: команда не найдена
kbuildsycoca4: командата не е открита
kbuildsycoca4: 命令找不到
kbuildsycoca4: コマンドが見つかりません