irclog2html: 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/irclog2html - from package: irclog2html

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

Error in other languages:
irclog2html: bevel nie gevind nie
irclog2html: comandă negăsită
irclog2html: comando não encontrado
irclog2html: commande introuvable
irclog2html: command not found
irclog2html: käsku ei ole
irclog2html: không tìm thấy lệnh
irclog2html: komanda nerasta
irclog2html: Kommando nicht gefunden.
irclog2html: kommandot finns inte
irclog2html: komut yok
irclog2html: nie znaleziono polecenia
irclog2html: níor aimsíodh an t-ordú
irclog2html: no se encontró la orden
irclog2html: no s'ha trobat l'ordre
irclog2html: opdracht niet gevonden
irclog2html: parancs nem található
irclog2html: perintah tidak ditemukan
irclog2html: príkaz nenájdený
irclog2html: příkaz nenalezen
irclog2html: команда не найдена
irclog2html: командата не е открита
irclog2html: 命令找不到
irclog2html: コマンドが見つかりません