antlr: 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/antlr - from package: antlr

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

On Debian possible default full paths are:

/usr/bin/antlr - from package: pccts

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

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