kfmclient: 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/kfmclient - from package: kdebase

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

On Debian possible default full paths are:

/usr/bin/kfmclient - from package: konqueror

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

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