redis-check-aof: 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/redis-check-aof - from package: redis

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

On Debian possible default full paths are:

/usr/bin/redis-check-aof - from package: redis-tools

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

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