jar: 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/jvm/java-1.5.0-gcj-4.8-amd64/bin/jar - from package: gcj-4.8-jdk
/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/bin/jar - from package: gcj-4.9-jdk
/usr/lib/debug/usr/lib/jvm/java-7-openjdk-amd64/bin/jar - from package: openjdk-7-dbg
/usr/lib/jvm/java-7-openjdk-amd64/bin/jar - from package: openjdk-7-jdk

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

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