irw: 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/irw - from package: lirc

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

On Debian possible default full paths are:

/usr/bin/irw - from package: lirc

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

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