lacheck: 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/lacheck - from package: texlive-latex

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

On Debian possible default full paths are:

/usr/bin/lacheck - from package: lacheck

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

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