hiredis-test: 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/hiredis-test - from package: hiredis

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

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