lhs2TeX: 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 Debian possible default full paths are:

/usr/bin/lhs2TeX - from package: lhs2tex

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

Error in other languages:
lhs2TeX: bevel nie gevind nie
lhs2TeX: comandă negăsită
lhs2TeX: comando não encontrado
lhs2TeX: commande introuvable
lhs2TeX: command not found
lhs2TeX: käsku ei ole
lhs2TeX: không tìm thấy lệnh
lhs2TeX: komanda nerasta
lhs2TeX: Kommando nicht gefunden.
lhs2TeX: kommandot finns inte
lhs2TeX: komut yok
lhs2TeX: nie znaleziono polecenia
lhs2TeX: níor aimsíodh an t-ordú
lhs2TeX: no se encontró la orden
lhs2TeX: no s'ha trobat l'ordre
lhs2TeX: opdracht niet gevonden
lhs2TeX: parancs nem található
lhs2TeX: perintah tidak ditemukan
lhs2TeX: príkaz nenájdený
lhs2TeX: příkaz nenalezen
lhs2TeX: команда не найдена
lhs2TeX: командата не е открита
lhs2TeX: 命令找不到
lhs2TeX: コマンドが見つかりません