xelatex: 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/xelatex - from package: texlive-xetex

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

On Debian possible default full paths are:

/usr/bin/xelatex - from package: texlive-xetex

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

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