zenmap: 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/zenmap - from package: nmap-frontend

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

On Debian possible default full paths are:

/usr/bin/zenmap - from package: zenmap

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

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