update-livereload: 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/update-livereload - from package: nodejs-tiny-lr-fork
/usr/lib/node_modules/tiny-lr-fork/bin/update-livereload - from package: nodejs-tiny-lr-fork

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

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