lesskey: 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/lesskey - from package: less

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

On Debian possible default full paths are:

/usr/bin/lesskey - from package: less
/bin/lesskey - from package: less

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

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