nmapfe: 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/nmapfe - from package: nmap-frontend

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

On Debian possible default full paths are:

/usr/bin/nmapfe - from package: zenmap

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

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