kwikdisk: 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/kwikdisk - from package: kdeutils

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

On Debian possible default full paths are:

/usr/bin/kwikdisk - from package: kdf

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

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