\n\n#include <stdlib.h>\r\n\r\nchar *getenv(const char *name<\/span>);\r\n<\/pre>\n<\/td>\n<\/tr>\n\n| \n Returns: pointer to value<\/span> associated with name<\/span>, NULL<\/tt> if not found<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\u6ce8\u610f\u8fd9\u4e2a\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a\u6307\u5411name=value<\/em>\u4e2dvalue\u7684\u6307\u9488\u3002\u5e94\u8be5\u4e00\u76f4\u4f7f\u7528getenv<\/span>\u83b7\u5f97\u5f97\u5b9a\u7684\u73af\u91cf\u53d8\u91cf\uff0c\u800c\u4e0d\u662f\u76f4\u63a5\u4f7f\u7528environ<\/span>\u3002<\/p>\n\u4e00\u4e9b\u73af\u5883\u53d8\u91cf\u88abPOSIX.1\u5b9a\u4e49\u5728Single UNIX Specification\u4e2d\uff0c\u53e6\u4e00\u4e9b\u5b9a\u4e49\u5728XSI\u6269\u5c55\u4e2d\u3002\u6ce8\u610f\uff1a<\/span>ISO C\u6ca1\u5b9a\u4e49\u4efb\u4f55\u73af\u5883\u53d8\u91cf\u3002<\/p>\n\u53e6\u5916\u6dfb\u52a0\u3001\u5220\u9664\u3001\u4fee\u6539\u73af\u5883\u53d8\u91cf\u5e76\u4e0d\u662f\u6240\u6709\u7cfb\u7edf\u90fd\u652f\u6301\uff1a<\/p>\n \n\n\n\n\n\nFigure 7.8. Support for various environment list functions<\/h5>\n<\/caption>\n\n\n\n\n\n\n\n<\/colgroup>\n\n\n| \n Function<\/span><\/p>\n<\/th>\n | \n ISO C<\/span><\/p>\n<\/th>\n | \n POSIX.1<\/span><\/p>\n<\/th>\n | \n FreeBSD 5.2.1<\/span><\/p>\n<\/th>\n | \n Linux 2.4.22<\/span><\/p>\n<\/th>\n | \n Mac OS X 10.3<\/span><\/p>\n<\/th>\n | \n Solaris 9<\/span><\/p>\n<\/th>\n<\/tr>\n<\/thead>\n\n\n| \n getenv<\/tt><\/p>\n<\/td>\n| \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n<\/tr>\n | \n| \n putenv<\/tt><\/p>\n<\/td>\n| <\/td>\n | \n XSI<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n<\/tr>\n | \n| \n setenv<\/tt><\/p>\n<\/td>\n| <\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | <\/td>\n<\/tr>\n | \n| \n unsetenv<\/tt><\/p>\n<\/td>\n| <\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | \n \u2022<\/p>\n<\/td>\n | <\/td>\n<\/tr>\n | \n| \n clearenv<\/tt><\/p>\n<\/td>\n| <\/td>\n | <\/td>\n | <\/td>\n | \n \u2022<\/p>\n<\/td>\n | <\/td>\n | <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n clearenv<\/tt><\/span> \u5e76\u4e0d\u662fsingle UNIX Specification\u4e2d\u7684\u4e00\u90e8\u5206\u3002\u5b83\u5e38\u88ab\u7528\u4e8e\u4ece\u73af\u5883\u53d8\u91cf\u5217\u8868\u4e2d\u5220\u9664\u6240\u6709\u5185\u5bb9\u3002<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\u4e0b\u9762\u662f\u4e09\u4e2a\u51fd\u6570\u7684\u539f\u578b\uff1a<\/p>\n\n\n\n\n #include <stdlib.h>\r\n\r\n int putenv(char *str<\/span>);\r\n\r\n int setenv(const char *name<\/span>, const char *value, <\/span> int rewrite<\/span>);\r\n\r\n int unsetenv(const char *name<\/span>);\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n\n| \n All return: 0 if OK, nonzero on error<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \u8fd9\u4e09\u4e2a\u51fd\u6570\u7684\u64cd\u4f5c\u5982\u4e0b\uff1a<\/p>\n \n- putenv<\/span>\u51fd\u6570\u7684\u53c2\u6570\u662f\u4e00\u4e2aname=value<\/em>\u7684\u5b57\u7b26\u4e32\uff0c\u5e76\u628a\u5b83\u653e\u5230\u73af\u5883\u53d8\u91cf\u7684\u5217\u8868\u91cc\u3002\u5982\u679cname<\/em>\u5df2\u7ecf\u5b58\u5728\uff0c\u5148\u5220\u9664\u4e4b\u524d\u7684\u5b9a\u4e49\u3002<\/li>\n
- setenv<\/span>\u51fd\u6570\u4e3avalue<\/em>\u8bbe\u7f6e\u4e00\u4e2aname<\/em>\u3002\u5982\u679cname<\/em>\u5df2\u7ecf\u5b58\u5728\u73af\u5883\u53d8\u91cf\u5217\u8868\u4e2d\uff1a\uff08a\uff09\u5982\u679crewrite<\/em>\u975e\u96f6\uff0c\u5df2\u7ecf\u5b58\u5728\u7684name<\/em>\u4f1a\u88ab\u5220\u9664\u3002\uff08b\uff09\u5982\u679crewrite<\/em>\u662f\u96f6\uff0c\u6c11\u7ecf\u5b58\u5728\u7684name<\/em>\u4fdd\u6301\u4e0d\u53d8\uff0c\u65b0\u503c\u4e5f\u4e0d\u4f1a\u88ab\u8bbe\u7f6e\uff0c\u800c\u4e14\u4e0d\u4f1a\u63d0\u793a\u9519\u8bef\u3002<\/li>\n
- unsetenv<\/span>\u51fd\u6570\u79fb\u9664\u4efb\u4f55\u5b9a\u4e49\u8fc7\u7684name<\/em>\u3002\u5982\u679cname<\/em>\u6ca1\u5b9a\u4e49\u8fc7\uff0c\u4e5f\u4e0d\u4f1a\u6709\u4efb\u4f55\u9519\u8bef\u63d0\u793a\u3002<\/li>\n<\/ul>\n
\u6ce8\u610fsetenv<\/span>\u548cputenv<\/span>\u4e4b\u95f4\u7684\u4e0d\u540c\u3002\u56e0\u4e3asetenv<\/span>\u4ece\u5b83\u7684\u53c2\u6570\u4e2d\u5efa\u7acbname=value<\/em>\u5b57\u7b26\u4e32\uff0c\u5fc5\u987b\u4e3a\u8be5\u5b57\u7b26\u4e32\u5206\u914d\u5185\u5b58\u3002\u800cputenv<\/span>\u662f\u76f4\u63a5\u628a\u5b57\u7b26\u4e32\u4f20\u7ed9\u73af\u5883\u53d8\u91cf\u3002\u5728linux\u548cSolaris\u4e0a\uff0cputenv<\/span>\u76f4\u63a5\u5c06\u53c2\u6570\u7684\u5b57\u7b26\u4e32\u5730\u5740\u4f20\u7ed9\u73af\u5883\u53d8\u91cf\u5217\u8868\u3002\u5728\u672c\u4f8b\u4e2d\uff0c\u4f20\u9012\u5728\u6808\u4e0a\u5206\u914d\u7684\u5b57\u7b26\u4e32\u5230\u73af\u5883\u53d8\u91cf\uff0c\u5f88\u6709\u53ef\u80fd\u53d1\u751f\u9519\u8bef<\/span>\uff0c\u56e0\u4e3a\u5728\u51fd\u6570\u8fd4\u56de\u540e\uff0c\u6808\u7684\u5730\u5740\u53ef\u80fd\u88ab\u91cd\u65b0\u4f7f\u7528\u3002<\/p>\n\u8fd9\u91cc\u4ecb\u7ecd\u5f53\u4fee\u6539\u73af\u5883\u53d8\u91cf\u5217\u8868\u65f6\uff0c\u8fd9\u4e9b\u51fd\u6570\u5982\u4f55\u64cd\u4f5c\u3002\u56de\u5fc6\u56fe7.6:<\/p>\n ![\"figure7.6\"](\"http:\/\/blog.5x44.cn\/wp-content\/uploads\/2016\/07\/QQ\u622a\u56fe20160720112902.jpg\") <\/p>\n
\u73af\u5883\u53d8\u91cf\u5217\u8868\u7684\u6307\u9488\u6570\u7ec4\uff08\u6bcf\u4e2a\u6307\u9488\u6307\u5411\u5b9e\u9645\u7684name=value<\/em>\u5b57\u7b26\u4e32\uff09\u548c\u73af\u5883\u53d8\u91cf\u5b57\u7b26\u4e32\u5178\u578b\u5b58\u50a8\u5728\u8fdb\u7a0b\u5185\u5b58\u7a7a\u95f4\u7684\u9876\u90e8\uff0c\u6808\u7684\u4e0a\u9762\u3002\u5220\u9664\u5b57\u7b26\u4e32\u5f88\u7b80\u5355\uff0c\u53ea\u8981\u5728\u73af\u5883\u53d8\u91cf\u5217\u8868\u4e2d\u627e\u5230\u8fd9\u4e2a\u6307\u9488\uff0c\u5e76\u79fb\u52a8\u6240\u6709\u5b50\u5e8f\u5217\u6307\u9488\u5411\u4e0b\u79fb\u52a8\u4e00\u4e2a\u4f4d\u7f6e\u3002\u53cd\u4e4b\u6dfb\u52a0\u6216\u4fee\u6539\u4e00\u4e2a\u5b57\u7b26\u4e32\u8981\u66f4\u56f0\u96be\u3002\u6808\u9876\u7684\u7a7a\u95f4\u4e0d\u80fd\u6269\u5c55\uff0c\u56e0\u4e3a\u5b83\u901a\u5e38\u662f\u5728\u8fdb\u7a0b\u7684\u5730\u5740\u7a7a\u95f4\u9876\u90e8\u3002\u540c\u6837\u4e5f\u4e0d\u80fd\u5411\u4e0b\u6269\u5c55\uff0c\u56e0\u4e3a\u6240\u6709\u5728\u4e0b\u9762\u7684\u6808\u5e27\u4e0d\u80fd\u79fb\u52a8\u3002<\/p>\n1.<\/strong>\u5982\u679c\u4fee\u6539\u4e00\u4e2a\u5b58\u5728\u7684name<\/em>\uff1a<\/p>\na<\/span>. \u5982\u679c\u65b0value<\/em>\u7684\u5c3a\u5bf8\u5c0f\u4e8e\u6216\u7b49\u4e8e\u5df2\u7ecf\u5b58\u5728\u7684\u503c\uff0c\u53ef\u4ee5\u4ec5\u590d\u5236\u65b0\u5b57\u7b26\u4e32\u8986\u76d6\u65e7\u7684\u3002<\/p>\nb<\/span>.\u5982\u679c\u65b0value<\/em>\u7684\u5c3a\u5bf8\u5927\u4e8e\u65e7\u7684\uff0c\u90a3\u5c31\u5fc5\u987b\u4e3a\u65b0\u503cmalloc<\/span>\u4e00\u4e2a\u7a7a\u95f4\uff0c\u590d\u5236\u65b0\u503c\u5230\u8fd9\u4e2a\u7a7a\u95f4\uff0c\u4e4b\u540e\u5728\u73af\u5883\u53d8\u91cf\u5217\u8868\u4e2d\u66ff\u6362\u65e7\u7684\u6307\u9488\u3002<\/p>\n2.\u5982\u679c\u8981\u6dfb\u52a0\u4e00\u4e2a\u65b0name<\/em>\uff0c\u8fd9\u4f1a\u66f4\u590d\u6742\u3002\u9996\u5148\uff0c\u5fc5\u987b\u4e3aname=value<\/em>\u5b57\u7b26\u4e32\u5206\u914d\u4e00\u4e2a\u65b0\u7684\u7a7a\u95f4\uff0c\u7136\u540e\u590d\u5236\u5b57\u7b26\u4e32\u5230\u8fd9\u4e2a\u533a\u57df\u3002<\/p>\na.<\/span>\u7136\u540e\uff0c\u5982\u679c\u8fd9\u662f\u7b2c\u4e00\u6b21\u6dfb\u52a0\u65b0name<\/em>\uff0c\u5fc5\u987b\u8c03\u7528malloc\u83b7\u5f97\u4e00\u4e2a\u65b0\u7684\u7a7a\u95f4\uff0c\u628a\u4e4b\u524d\u73af\u5883\u53d8\u91cf\u5217\u8868\u590d\u5236\u5230\u8fd9\u4e2a\u65b0\u7a7a\u95f4\uff0c\u7136\u540e\u5728\u8fd9\u4e2a\u6307\u9488\u6570\u7ec4\u7684\u7ed3\u5c3e\u5b58\u50a8\u4e00\u4e2a\u6307\u5411name=value<\/em>\u5b57\u7b26\u4e32\u7684\u6307\u9488\u3002\u6700\u540e\uff0c\u4f7f\u7528environ<\/span>\u6307\u5411\u8fd9\u4e2a\u65b0\u7684\u6307\u9488\u6570\u7ec4\u3002\u6ce8\u610f\uff0c\u5982\u56fe7.6\u6240\u793a\uff0c\u5982\u679c\u539f\u59cb\u7684\u73af\u5883\u53d8\u91cf\u5217\u8868\u5df2\u7ecf\u5305\u542b\u5728\u6808\u9876\u4e4b\u4e0a\u3002\u90a3\u4e48\u5fc5\u987b\u79fb\u52a8\u8fd9\u4e2a\u6307\u9488\u5217\u8868\u5230\u5806\uff0c\u4f46\u8fd9\u4e2a\u5217\u8868\u4e2d\u7684\u591a\u6570\u6307\u9488\u4f9d\u7136\u6307\u5411\u6808\u9876\u4e4b\u4e0a\u7684\u5b57\u7b26\u4e32\u3002<\/p>\nb.\u5982\u679c\u8fd9\u4e0d\u662f\u7b2c\u4e00\u6b21\u6dfb\u52a0\u65b0name<\/em>\uff0c\u90a3\u4e5f\u5c31\u662f\u8bf4\u4e4b\u524d\u5df2\u7ecf\u5728\u5806\u4e0a\u5206\u914d\u4e86\u7a7a\u95f4\uff0c\u6240\u4ee5\u53ea\u8981\u8c03\u7528recalloc<\/span>\u53bb\u6269\u5c55\u7a7a\u95f4\u7684\u5927\u5c0f\u5c31\u53ef\u4ee5\u4e86\u3002\u6307\u5411\u65b0\u7684name=value<\/em>\u5b57\u7b26\u4e32\u7684\u6307\u9488\uff0c\u88ab\u5b58\u50a8\u5728\u5217\u8868\u7684\u7ed3\u5c3e\uff08\u5728\u4e4b\u524d\u7a7a\u6307\u9488\u7684\u4e0a\u9762\uff09\uff0c\u5b83\u7684\u540e\u9762\u518d\u8ddf\u4e00\u4e2a\u7a7a\u6307\u9488\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"\u73af\u5883\u53d8\u91cf\u901a\u5e38\u662f\u8fd9\u6837\u7684\u5f62\u5f0f\uff1a name=value UNIX\u5185\u6838\u4e0d\u7406\u4f1a\u5b83\u7684\u540d\u5b57\uff0c\u53ea\u628a\u5b83\u89e3\u91ca\u7ed9\u591a\u79cd\u5e94\u7528\u7a0b\u5e8f\u3002 ISO C\u5b9a\u4e49\u4e86\u5f97\u5230\u73af\u5883\u53d8\u91cf\u503c\u7684\u51fd\u6570\uff0c\u4f46\u662f\u73af\u5883\u53d8\u91cf\u7684\u503c…<\/p>\n Read More Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[],"class_list":["post-321","post","type-post","status-publish","format-standard","hentry","category-apue"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/321","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=321"}],"version-history":[{"count":17,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/321\/revisions"}],"predecessor-version":[{"id":339,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/321\/revisions\/339"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=321"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=321"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=321"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} 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