ikiwiki-comment: 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/ikiwiki-comment - from package: ikiwiki

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

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