Comment 2 for bug 175420

I have the same problem:

bibliotheque@bibliotheque:~$ apt-get install flash-plugin-nonfree
E: Impossible d'ouvrir le fichier verrou /var/lib/dpkg/lock - open (13 Permission non accordée)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
bibliotheque@bibliotheque:~$ sudo apt-get install flash-plugin-nonfree
[sudo] password for bibliotheque:
E: Impossible de verrouiller /var/lib/dpkg/lock - open (11 Ressource temporairement non disponible)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
bibliotheque@bibliotheque:~$ sudo apt-get install flash-plugin-nonfree
E: Impossible de verrouiller /var/lib/dpkg/lock - open (11 Ressource temporairement non disponible)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
bibliotheque@bibliotheque:~$ sudo apt-get install flash-plugin-nonfree
E: Impossible de verrouiller /var/lib/dpkg/lock - open (11 Ressource temporairement non disponible)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?
bibliotheque@bibliotheque:~$ sudo apt-get install flash-plugin-nonfree
Lecture des listes de paquets... Fait
Construction de l'arbre des dépendances
Lecture des informations d'état... Fait
E: Impossible de trouver le paquet flash-plugin-nonfree
bibliotheque@bibliotheque:~$ sudo apt-get install flashplugin-nonfree
Lecture des listes de paquets... Fait
Construction de l'arbre des dépendances
Lecture des informations d'état... Fait
Paquets suggérés :
  konqueror-nsplugins msttcorefonts ttf-xfree86-nonfree xfs
Les NOUVEAUX paquets suivants seront installés :
  flashplugin-nonfree
0 mis à jour, 1 nouvellement installés, 0 à enlever et 0 non mis à jour.
Il est nécessaire de prendre 0o/18,1ko dans les archives.
Après dépaquetage, 160ko d'espace disque supplémentaires seront utilisés.
Préconfiguration des paquets...
Sélection du paquet flashplugin-nonfree précédemment désélectionné.
(Lecture de la base de données... 89721 fichiers et répertoires déjà installés.)
Dépaquetage de flashplugin-nonfree (à partir de .../flashplugin-nonfree_9.0.48.0.2+really0ubuntu12_i386.deb) ...
Paramétrage de flashplugin-nonfree (9.0.48.0.2+really0ubuntu12) ...
Downloading...
--08:46:43-- http://fpdownload.macromedia.com/get/flashplayer/current/install_flash_player_9_linux.tar.gz
           => `./install_flash_player_9_linux.tar.gz'
Résolution de fpdownload.macromedia.com... 88.221.22.70
Connexion vers fpdownload.macromedia.com|88.221.22.70|:80... connecté.
requête HTTP transmise, en attente de la réponse... 200 OK
Longueur: 3 036 127 (2.9M) [application/x-gzip]

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08:47:14 (96.86 KB/s) - « ./install_flash_player_9_linux.tar.gz » sauvegardé [3036127/3036127]

Download done.
md5sum mismatch install_flash_player_9_linux.tar.gz
The Flash plugin is NOT installed.