konqueror: 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/konqueror - from package: kdebase

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

On Debian possible default full paths are:

/usr/bin/konqueror - from package: konqueror

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

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