json_diff: 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/json_diff - from package: json_diff

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

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