{"id":28,"date":"2020-06-15T18:39:33","date_gmt":"2020-06-15T22:39:33","guid":{"rendered":"https:\/\/sites.temple.edu\/vahid\/?p=28"},"modified":"2020-06-15T18:39:33","modified_gmt":"2020-06-15T22:39:33","slug":"executables-and-libraries","status":"publish","type":"post","link":"https:\/\/sites.temple.edu\/vahid\/2020\/06\/15\/executables-and-libraries\/","title":{"rendered":"Executables and Libraries"},"content":{"rendered":"\n

Static and dynamic link libraries (or shared object files) are two essential components in modern operating systems.<\/p>\n\n\n\n

Linux has very interesting tools to interact with executable files and corresponding libraries. The following quick note comes from the following link.<\/p>\n\n\n\n

https:\/\/amir.rachum.com\/blog\/2016\/09\/17\/shared-libraries\/<\/a><\/p>\n\n\n\n

$ readelf -h main<\/code><\/p>\n\n\n\n

can be used to find header information about the executable.<\/p>\n\n\n\n

$ readelf -d main | grep NEEDED<\/code><\/p>\n\n\n\n

can be used to show the dependency of the executable to libraries.<\/p>\n\n\n\n

$ ldd main<\/code><\/p>\n\n\n\n

will show the dependency hierarchy<\/em><\/strong> of an executable.<\/p>\n\n\n\n

Each shared library in our dependencies is searched in the following locations, in order:<\/p>\n\n\n\n

  1. Directories listed in the executable\u2019s rpath<\/span><\/code>.<\/li>
  2. Directories in the LD_LIBRARY_PATH<\/span><\/code> environment variable, which contains colon-separated list of directories (e.g., \/path\/to\/libdir:\/another\/path)<\/li>
  3. Directories listed in the executable\u2019s runpath<\/span><\/code>.<\/li>
  4. The list of directories in the file \/etc\/ld.so.conf<\/span><\/code>. This file can include other files, but it is basically a list of directories – one per line.<\/li>
  5. Default system libraries – usually \/lib<\/span><\/code> and \/usr\/lib<\/code><\/span> (skipped if compiled with -z nodefaultlib<\/code>).<\/li><\/ol>\n\n\n\n

    $echo $LD_LIBRARY_PATH<\/code><\/p>\n\n\n\n

    can be used to show the current default search paths to find shared libraries.<\/p>\n\n\n\n

    <\/p>\n","protected":false},"excerpt":{"rendered":"

    Static and dynamic link libraries (or shared object files) are two essential components in modern operating systems. Linux has very interesting tools to interact with…<\/p>\n

    Continue readingExecutables and Libraries<\/span><\/a><\/div>\n","protected":false},"author":18759,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14],"tags":[25,27,24],"class_list":["post-28","post","type-post","status-publish","format-standard","hentry","category-tools","tag-c","tag-libraries","tag-linux","entry"],"_links":{"self":[{"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/posts\/28","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/users\/18759"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/comments?post=28"}],"version-history":[{"count":0,"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/posts\/28\/revisions"}],"wp:attachment":[{"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/media?parent=28"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/categories?post=28"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sites.temple.edu\/vahid\/wp-json\/wp\/v2\/tags?post=28"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}