jhat: 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/lib/debug/usr/lib/jvm/java-7-openjdk-amd64/bin/jhat - from package: openjdk-7-dbg
/usr/lib/jvm/java-7-openjdk-amd64/bin/jhat - from package: openjdk-7-jdk

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

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