{"id":443,"date":"2016-08-30T16:49:12","date_gmt":"2016-08-30T08:49:12","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=443"},"modified":"2016-12-01T15:27:19","modified_gmt":"2016-12-01T07:27:19","slug":"system%e5%87%bd%e6%95%b0","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=443","title":{"rendered":"system\u51fd\u6570"},"content":{"rendered":"

system<\/span>\u51fd\u6570\u7528\u4e8e\u6267\u884c\u4e00\u4e2a\u547d\u4ee4\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\u83b7\u5f97\u65f6\u95f4\u548c\u65e5\u671f\uff1a<\/p>\n

system(“date > file”);<\/span><\/p>\n

\u867d\u7136ISO C\u5b9a\u4e49\u4e86system<\/span>\u51fd\u6570\uff0c\u4f46\u662f\u5b83\u7684\u64cd\u4f5c\u975e\u5e38\u4f9d\u8d56\u7cfb\u7edf\u3002POSIX.1\u5305\u542b\u4e86system<\/span>\u63a5\u53e3\uff0c\u5728POSIX\u73af\u5883\u4e2d\u6269\u5c55\u4e86\u5b83\u5728ISO C\u4e2d\u5b9a\u4e49\u7684\u884c\u4e3a\u3002<\/p>\n\n\n\n\n
\n
#include <stdlib.h>\r\n\r\nint system(const char *cmdstring<\/span>);\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n
\n

Returns: (see below)<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u5982\u679ccmdstring<\/em>\u662fnull\u6307\u9488\uff0c\u4ec5\u5f53\u6307\u4ee4\u5904\u7406\u5668<\/span>\u53ef\u7528\u65f6\uff0csystem<\/span>\u8fd4\u56de\u975e\u96f6\u3002\u8fd9\u4e2a\u529f\u80fd\u7528\u4e8e\u6d4b\u8bd5system<\/span>\u51fd\u6570\u662f\u5426\u652f\u6301\u5f53\u524d\u64cd\u4f5c\u7cfb\u7edf\u3002\u5728UNIX\u7cfb\u7edf\u4e0b\uff0csystem<\/span>\u4e00\u76f4\u53ef\u7528\u3002<\/p>\n

\u56e0\u4e3asystem<\/span>\u51fd\u6570\u7531fork<\/span>, exec<\/span>\u548cwaitpid<\/span>\u5b9e\u73b0\uff0c\u6240\u4ee5\u8fd9\u91cc\u6709\u4e09\u79cd\u8fd4\u56de\u503c\uff1a<\/p>\n

    \n
  1. \u5982\u679cfork<\/span>\u5931\u8d25\u6216waitpid<\/span>\u8fd4\u56deEINTR<\/span>\u4e4b\u5916\u7684\u9519\u8bef\uff0csystem<\/span>\u8fd4\u56de1\uff0c\u5e76\u4e14errno<\/span>\u6307\u660e\u76f8\u5e94\u7684\u9519\u8bef\u3002<\/li>\n
  2. \u5982\u679cexec<\/span>\u5931\u8d25\uff0c\u8fd9\u8bf4\u660eshell\u4e0d\u80fd\u6267\u884c\u8be5\u547d\u4ee4\uff0c\u5176\u8fd4\u56de\u503c\u5982\u540cshell\u6267\u884c\u4e86exit(127)<\/span>\u4e00\u6837\u3002<\/li>\n
  3. \u5176\u5b83\uff0c\u6240\u6709\u4e09\u4e2a\u51fd\u6570\uff08fork\uff0cexec\u548cwaitpid\uff09\u90fd\u6210\u529f\u4e86\uff0csystem\u7684\u8fd4\u56de\u503c\u662fshell\u7684\u7ec8\u7aef\u72b6\u6001\u3002\uff08\u7b26\u5408waitpid<\/span>\u7684\u53c2\u6570\u683c\u5f0f\uff09<\/li>\n<\/ol>\n

    \u4f7f\u7528system<\/span>\u4ee3\u66ff\u76f4\u63a5\u4f7f\u7528fork<\/span>\u548cexec<\/span>\u7684\u4f18\u70b9\u662f\uff1asystem<\/span>\u5904\u7406\u4e86\u6240\u6709\u7684\u9519\u8bef\u548c\u4fe1\u53f7\u8bf7\u6c42\u3002<\/p>\n

    Set-User-ID\u7a0b\u5e8f<\/h2>\n

    \u5982\u679c\u5728\u4e00\u4e2a\u8bbe\u7f6e\u4e86SUID\u7684\u7a0b\u5e8f\u91cc\u8c03\u7528system<\/span>\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1f\u8fd9\u4e48\u505a\u662f\u4e00\u4e2a\u5b89\u5168\u6f0f\u6d1e\uff0c\u6240\u4ee5\u6c38\u8fdc<\/em><\/span>\u4e0d\u8981\u8fd9\u4e48\u505a\u3002<\/p>\n

    \u5982\u679c\u8bbe\u7f6e\u4e86SUID\u7684\u7a0b\u5e8f\u62e5\u6709\u8d85\u7ea7\u7528\u6237\u6743\u9650\u7684\u8bdd\uff0c\u90a3\u4e48\u5b83\u7684\u6743\u9650\u4f1a\u88ab\u4fdd\u7559\u4e0b\u6765\uff0c\u4e5f\u5c31\u662f\u8bf4system<\/span>\u6267\u884c\u7684\u547d\u4ee4\u4f1a\u4ee5\u8d85\u7ea7\u7528\u6237\u7684\u8eab\u4efd\u6267\u884c\u3002\uff08\u5f53\/bin\/sh<\/span>\u662fbash<\/span>\u7248\u672c2\u65f6\uff0c\u8fd9\u4e0d\u4f1a\u53d1\u751f\uff0c\u56e0\u4e3a\u5728\u6709\u6548\u7528\u6237ID\u548c\u5b9e\u9645\u7528\u6237ID\u4e0d\u540c\u65f6\uff0cbash\u4f1a\u91cd\u7f6e\u6709\u6548\u7528\u6237ID\u548c\u5b9e\u9645\u7528\u6237ID\uff09\u5982\u679c\u7a0b\u5e8f\u8981\u8fd9\u4e48\u505a\u7684\u8bdd\uff0c\u8bf7\u76f4\u63a5\u4f7f\u7528fork<\/span>\u548cexec<\/span>\uff0c\u5728exec<\/span>\u540e\u628a\u6743\u9650\u8bbe\u7f6e\u56de\u666e\u901a\u7528\u6237\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

    system\u51fd\u6570\u7528\u4e8e\u6267\u884c\u4e00\u4e2a\u547d\u4ee4\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\u83b7\u5f97\u65f6\u95f4\u548c\u65e5\u671f\uff1a system(“date > file”); \u867d\u7136ISO C\u5b9a\u4e49\u4e86s…<\/p>\n

    Read More Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[],"class_list":["post-443","post","type-post","status-publish","format-standard","hentry","category-apue"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/443","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=443"}],"version-history":[{"count":6,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/443\/revisions"}],"predecessor-version":[{"id":463,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/443\/revisions\/463"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=443"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=443"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=443"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}