chkhelp: 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/libexec/pcp/bin/chkhelp - from package: pcp

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/chkhelp - from package: pcp

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

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