jtdiff: 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/jtdiff - from package: jtreg

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

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