xfontsel: 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/xfontsel - from package: xorg-x11-apps

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

On Debian possible default full paths are:

/usr/bin/xfontsel - from package: x11-utils

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

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