ocamllex: 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/ocamllex - from package: ocaml

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

On Debian possible default full paths are:

/usr/bin/ocamllex - from package: ocaml-nox

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

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