irclogsearch: 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/irclogsearch - from package: irclog2html

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

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