Error running sudo

Binary package hint: sudo

Hi,

My graphical login doesn't work (it begins to open kde session and then bounces back to login screen).

So I hit CTRL+Alt+F1 and tried command line. Login is fine and tells me I need to upgrade some packages so I run sudo apt-get update and there it begins :

sudo apt-get update
/usr/bin/sudo: line 1: dead_caron, : commande introuvable
/usr/bin/sudo: line 1: // : ceci est un répertoire
/usr/bin/sudo: line 1: 1 : commande introuvable
/usr/bin/sudo: line 13: Erreur de syntaxe près du symbole inattendu « ) »
/usr/bin/sudo: line 13: `"&)�7�?<*(@
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I've looked all over the place but found no bug like that one.