{"id":2449,"date":"2025-08-23T18:05:29","date_gmt":"2025-08-23T16:05:29","guid":{"rendered":"https:\/\/artheodoc.fr\/?page_id=2449"},"modified":"2025-08-23T18:08:15","modified_gmt":"2025-08-23T16:08:15","slug":"la-commande-dmesg-sous-linux","status":"publish","type":"page","link":"https:\/\/artheodoc.fr\/index.php\/la-commande-dmesg-sous-linux\/","title":{"rendered":"La commande dmesg sous Linux"},"content":{"rendered":"\n<p class=\"has-pale-ocean-gradient-background has-background\"><em>La commande dmesg sous Linux est un outil essentiel pour consulter les messages du noyau (kernel). Elle permet d&rsquo;afficher le tampon d&rsquo;anneau (ring buffer) du noyau, qui contient des informations sur le mat\u00e9riel d\u00e9tect\u00e9, les erreurs syst\u00e8me, les pilotes charg\u00e9s, les p\u00e9riph\u00e9riques connect\u00e9s, et d&rsquo;autres \u00e9v\u00e9nements importants li\u00e9s au fonctionnement du syst\u00e8me.<\/em><\/p>\n\n\n\n<p>\u00c0 quoi sert dmesg&nbsp;?<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Diagnostic mat\u00e9riel&nbsp;: V\u00e9rifier si un p\u00e9riph\u00e9rique (cl\u00e9 USB, disque dur, carte r\u00e9seau, etc.) est correctement reconnu par le noyau.<\/li>\n\n\n\n<li>D\u00e9bogage&nbsp;: Identifier des erreurs mat\u00e9rielles ou logicielles (ex.&nbsp;: probl\u00e8mes de pilotes, conflits de ressources).<\/li>\n\n\n\n<li>Surveillance du syst\u00e8me&nbsp;: Voir les \u00e9v\u00e9nements li\u00e9s au d\u00e9marrage ou \u00e0 l&rsquo;arr\u00eat du syst\u00e8me.<\/li>\n\n\n\n<li>Analyse des performances&nbsp;: Rep\u00e9rer des messages d&rsquo;avertissement ou d&rsquo;erreur qui pourraient impacter les performances.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<p>Comment utiliser dmesg&nbsp;?<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">1. Afficher tous les messages du noyau&nbsp;:<\/h2>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg<\/pre>\n\n\n\n<p><strong>Remarque<\/strong>&nbsp;: La sortie peut \u00eatre tr\u00e8s longue. Utilisez un paginateur comme <strong>less<\/strong>&nbsp;:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg | less<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">2. Filtrer les messages par niveau de gravit\u00e9&nbsp;:<\/h2>\n\n\n\n<p>Les messages du noyau sont class\u00e9s par niveau de gravit\u00e9 (priorit\u00e9). Voici les niveaux les plus courants&nbsp;:<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-regular\"><table class=\"has-fixed-layout\"><tbody><tr><th>Niveau<\/th><th>Valeur<\/th><th>Description<\/th><\/tr><tr><td>emerg<\/td><td>0<\/td><td>Le syst\u00e8me est inutilisable.<\/td><\/tr><tr><td>alert<\/td><td>1<\/td><td>Une action imm\u00e9diate est n\u00e9cessaire.<\/td><\/tr><tr><td>crit<\/td><td>2<\/td><td>Condition critique (ex.&nbsp;: panique du noyau).<\/td><\/tr><tr><td>err<\/td><td>3<\/td><td>Erreur mat\u00e9rielle ou logicielle.<\/td><\/tr><tr><td>warning<\/td><td>4<\/td><td>Avertissement (probl\u00e8me potentiel).<\/td><\/tr><tr><td>notice<\/td><td>5<\/td><td>\u00c9v\u00e9nement normal mais important.<\/td><\/tr><tr><td>info<\/td><td>6<\/td><td>Message informatif.<\/td><\/tr><tr><td>debug<\/td><td>7<\/td><td>Message de d\u00e9bogage (utile pour les d\u00e9veloppeurs).<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>Exemple<\/strong>&nbsp;: Afficher uniquement les erreurs (<strong>err<\/strong>)&nbsp;:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg --level=err<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">3. Afficher les messages en temps r\u00e9el&nbsp;:<\/h2>\n\n\n\n<p>Pour surveiller les nouveaux messages au fur et \u00e0 mesure qu&rsquo;ils apparaissent&nbsp;:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg --follow<\/pre>\n\n\n\n<p>\u00c9quivalent \u00e0 tail -f \/var\/log\/dmesg<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">4. Rechercher un mot-cl\u00e9 sp\u00e9cifique&nbsp;:<\/h2>\n\n\n\n<p>Utilisez grep pour filtrer les messages&nbsp;:<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg | grep -i \"usb\"<\/pre>\n\n\n\n<p>Affiche tous les messages li\u00e9s aux p\u00e9riph\u00e9riques USB.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">5. Limiter le nombre de lignes affich\u00e9es&nbsp;:<\/h2>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg | head -n 20<\/pre>\n\n\n\n<p>Affiche uniquement les 20 premi\u00e8res lignes.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">6. Afficher les messages avec un horodatage lisible&nbsp;:<\/h2>\n\n\n\n<pre class=\"wp-block-preformatted\">dmesg --human --time-format ctime<\/pre>\n\n\n\n<p>Affiche les messages avec une date et une heure lisibles.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">7. Effacer le tampon du noyau&nbsp;:<\/h2>\n\n\n\n<p><strong>Attention<\/strong>&nbsp;: Cette commande efface les messages du tampon. Utilisez-la avec prudence.<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\">sudo dmesg --clear<\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">O\u00f9 sont stock\u00e9s les messages de dmesg&nbsp;?&nbsp;:<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Les messages sont stock\u00e9s dans le tampon du noyau (en m\u00e9moire).<\/li>\n\n\n\n<li>Ils sont aussi souvent enregistr\u00e9s dans le fichier&nbsp;:<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-preformatted\">\/var\/log\/dmesg<\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Certains syst\u00e8mes utilisent journalctl (avec systemd) pour consulter les logs du noyau&nbsp;:<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-preformatted\">journalctl -k<\/pre>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><th>Commande<\/th><th>Apr\u00e8s le pipe |<\/th><\/tr><tr><td>dmesg<\/td><td>grep -i \u00ab\u00a0error\u00a0\u00bb<\/td><\/tr><tr><td>dmesg<\/td><td>grep -i \u00ab\u00a0eth0\u00a0\u00bb<\/td><\/tr><tr><td>dmesg<\/td><td>grep -i \u00ab\u00a0sda\u00a0\u00bb<\/td><\/tr><tr><td>dmesg<\/td><td>tail -n 50<\/td><\/tr><tr><td>dmesg &#8211;level=err,warn<\/td><td><em>Afficher uniquement les erreurs et avertissements.<\/em><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">R\u00e9sum\u00e9&nbsp;:<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>dmesg est un outil puissant pour diagnostiquer des probl\u00e8mes mat\u00e9riels ou logiciels.<\/li>\n\n\n\n<li>Utilisez des filtres (grep, &#8211;level) pour cibler les informations utiles.<\/li>\n\n\n\n<li>Combinez avec less, head, ou tail pour une lecture plus facile.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity is-style-wide\"\/>\n\n\n\n<p>Sources&nbsp;: Le Chat Mistral<\/p>\n\n\n\n<p><a href=\"https:\/\/chat.mistral.ai\/chat\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/chat.mistral.ai\/chat<\/a><\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>La commande dmesg sous Linux est un outil essentiel pour consulter les messages du noyau (kernel). Elle permet d&rsquo;afficher le tampon d&rsquo;anneau (ring buffer) du noyau, qui contient des informations sur le mat\u00e9riel d\u00e9tect\u00e9, les erreurs syst\u00e8me, les pilotes charg\u00e9s, les p\u00e9riph\u00e9riques connect\u00e9s, et d&rsquo;autres \u00e9v\u00e9nements importants li\u00e9s au fonctionnement du syst\u00e8me. \u00c0 quoi sert [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-2449","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/pages\/2449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/comments?post=2449"}],"version-history":[{"count":2,"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/pages\/2449\/revisions"}],"predecessor-version":[{"id":2453,"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/pages\/2449\/revisions\/2453"}],"wp:attachment":[{"href":"https:\/\/artheodoc.fr\/index.php\/wp-json\/wp\/v2\/media?parent=2449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}