Thanks for the detail, indeed it was fixed in https://packages.qa.debian.org/s/shared-mime- info/news/20150919T193529Z.html
The new package has been synced to Ubuntu https://launchpad.net/ubuntu/+source/shared-mime-info/1.5-2 ** Changed in: shared-mime-info (Ubuntu) Importance: Undecided => High ** Changed in: shared-mime-info (Ubuntu) Status: Incomplete => Fix Released -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to shared-mime-info in Ubuntu. https://bugs.launchpad.net/bugs/1485217 Title: Magic for text/x-tex broken Status in shared-mime-info package in Ubuntu: Fix Released Bug description: The magic for text/x-tex in Ubuntu 15.04 is broken as it assigns text/x-tex to any text file which contains the word "section", "chapter" or "documentclass" within the first 100 characters. This behavior is fixed if one adds backslashes to the appropriate match values in /usr/share/mime/packages/freedesktop.org.xml (.in) (see attached patch). Edit: You can reproduce this bug as follows. Is (output on Ubuntu 15.04): user@host:/tmp/mime$ dpkg -s shared-mime-info | grep "Version" Version: 1.3-1 user@host:/tmp/mime$ sed '30568,30638!d' /usr/share/mime/packages/freedesktop.org.xml <mime-type type="text/x-tex"> <comment>TeX document</comment> <comment xml:lang="ar">مستند TeX</comment> <comment xml:lang="be@latin">Dakument TeX</comment> <comment xml:lang="bg">Документ — TeX</comment> <comment xml:lang="ca">document TeX</comment> <comment xml:lang="cs">Dokument TeX</comment> <comment xml:lang="cy">Dogfen TeX </comment> <comment xml:lang="da">TeX-dokument</comment> <comment xml:lang="de">TeX-Dokument</comment> <comment xml:lang="el">έγγραφο TeX</comment> <comment xml:lang="en_GB">TeX document</comment> <comment xml:lang="eo">TeX-dokumento</comment> <comment xml:lang="es">documento TeX</comment> <comment xml:lang="eu">TeX dokumentua</comment> <comment xml:lang="fi">TeX-asiakirja</comment> <comment xml:lang="fo">TeX skjal</comment> <comment xml:lang="fr">document TeX</comment> <comment xml:lang="ga">cáipéis TeX</comment> <comment xml:lang="gl">documenton TeX</comment> <comment xml:lang="he">מסמך TeX</comment> <comment xml:lang="hr">TeX dokument</comment> <comment xml:lang="hu">TeX-dokumentum</comment> <comment xml:lang="id">Dokumen TeX</comment> <comment xml:lang="it">Documento TeX</comment> <comment xml:lang="ja">TeX ドキュメント</comment> <comment xml:lang="kk">TeX құжаты</comment> <comment xml:lang="ko">TeX 문서</comment> <comment xml:lang="lt">TeX dokumentas</comment> <comment xml:lang="lv">TeX dokuments</comment> <comment xml:lang="ms">Dokumen TeX</comment> <comment xml:lang="nb">TeX-dokument</comment> <comment xml:lang="nl">TeX-document</comment> <comment xml:lang="nn">TeX-dokument</comment> <comment xml:lang="pl">Dokument TeX</comment> <comment xml:lang="pt">documento TeX</comment> <comment xml:lang="pt_BR">Documento TeX</comment> <comment xml:lang="ro">Document TeX</comment> <comment xml:lang="ru">документ TeX</comment> <comment xml:lang="sk">Dokument TeX</comment> <comment xml:lang="sl">Dokument TeX</comment> <comment xml:lang="sq">Dokument TeX</comment> <comment xml:lang="sr">ТеХ документ</comment> <comment xml:lang="sv">TeX-dokument</comment> <comment xml:lang="tr">TeX belgesi</comment> <comment xml:lang="uk">документ TeX</comment> <comment xml:lang="vi">Tài liệu TeX</comment> <comment xml:lang="zh_CN">TeX 文档</comment> <comment xml:lang="zh_TW">TeX 文件</comment> <sub-class-of type="text/plain"/> <alias type="application/x-tex"/> <glob pattern="*.tex"/> <glob pattern="*.ltx"/> <glob pattern="*.sty"/> <glob pattern="*.cls"/> <glob pattern="*.dtx"/> <glob pattern="*.ins"/> <glob pattern="*.latex"/> <magic priority="10"> <match value="%" type="string" offset="0"/> </magic> <magic priority="50"> <match value="\documentclass" type="string" offset="0:100"/> </magic> <magic priority="50"> <match value="\chapter" type="string" offset="0:100"/> </magic> <magic priority="50"> <match value="\section" type="string" offset="0:100"/> </magic> </mime-type> user@host:/tmp/mime$ echo "Normal text using 'sectional'." > no_tex user@host:/tmp/mime$ mimetype no_tex no_tex: text/x-tex user@host:/tmp/mime$ echo "\section{A \TeX Section}" > tex_file.tex user@host:/tmp/mime$ mimetype tex_file.tex tex_file.tex: text/x-tex Should (is, after patching): user@host:/tmp/mime$ sed '30568,30638!d' /usr/share/mime/packages/freedesktop.org.xml <mime-type type="text/x-tex"> <comment>TeX document</comment> <comment xml:lang="ar">مستند TeX</comment> <comment xml:lang="be@latin">Dakument TeX</comment> <comment xml:lang="bg">Документ — TeX</comment> <comment xml:lang="ca">document TeX</comment> <comment xml:lang="cs">Dokument TeX</comment> <comment xml:lang="cy">Dogfen TeX </comment> <comment xml:lang="da">TeX-dokument</comment> <comment xml:lang="de">TeX-Dokument</comment> <comment xml:lang="el">έγγραφο TeX</comment> <comment xml:lang="en_GB">TeX document</comment> <comment xml:lang="eo">TeX-dokumento</comment> <comment xml:lang="es">documento TeX</comment> <comment xml:lang="eu">TeX dokumentua</comment> <comment xml:lang="fi">TeX-asiakirja</comment> <comment xml:lang="fo">TeX skjal</comment> <comment xml:lang="fr">document TeX</comment> <comment xml:lang="ga">cáipéis TeX</comment> <comment xml:lang="gl">documenton TeX</comment> <comment xml:lang="he">מסמך TeX</comment> <comment xml:lang="hr">TeX dokument</comment> <comment xml:lang="hu">TeX-dokumentum</comment> <comment xml:lang="id">Dokumen TeX</comment> <comment xml:lang="it">Documento TeX</comment> <comment xml:lang="ja">TeX ドキュメント</comment> <comment xml:lang="kk">TeX құжаты</comment> <comment xml:lang="ko">TeX 문서</comment> <comment xml:lang="lt">TeX dokumentas</comment> <comment xml:lang="lv">TeX dokuments</comment> <comment xml:lang="ms">Dokumen TeX</comment> <comment xml:lang="nb">TeX-dokument</comment> <comment xml:lang="nl">TeX-document</comment> <comment xml:lang="nn">TeX-dokument</comment> <comment xml:lang="pl">Dokument TeX</comment> <comment xml:lang="pt">documento TeX</comment> <comment xml:lang="pt_BR">Documento TeX</comment> <comment xml:lang="ro">Document TeX</comment> <comment xml:lang="ru">документ TeX</comment> <comment xml:lang="sk">Dokument TeX</comment> <comment xml:lang="sl">Dokument TeX</comment> <comment xml:lang="sq">Dokument TeX</comment> <comment xml:lang="sr">ТеХ документ</comment> <comment xml:lang="sv">TeX-dokument</comment> <comment xml:lang="tr">TeX belgesi</comment> <comment xml:lang="uk">документ TeX</comment> <comment xml:lang="vi">Tài liệu TeX</comment> <comment xml:lang="zh_CN">TeX 文档</comment> <comment xml:lang="zh_TW">TeX 文件</comment> <sub-class-of type="text/plain"/> <alias type="application/x-tex"/> <glob pattern="*.tex"/> <glob pattern="*.ltx"/> <glob pattern="*.sty"/> <glob pattern="*.cls"/> <glob pattern="*.dtx"/> <glob pattern="*.ins"/> <glob pattern="*.latex"/> <magic priority="10"> <match value="%" type="string" offset="0"/> </magic> <magic priority="50"> <match value="\\documentclass" type="string" offset="0:100"/> </magic> <magic priority="50"> <match value="\\chapter" type="string" offset="0:100"/> </magic> <magic priority="50"> <match value="\\section" type="string" offset="0:100"/> </magic> </mime-type> user@host:/tmp/mime$ echo "Normal text using 'sectional'." > no_tex user@host:/tmp/mime$ mimetype no_tex no_tex: text/plain user@host:/tmp/mime$ echo "\section{A \TeX Section}" > tex_file.tex user@host:/tmp/mime$ mimetype tex_file.tex tex_file.tex: text/x-tex To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shared-mime-info/+bug/1485217/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp