{"id":44688,"date":"2024-10-06T17:27:20","date_gmt":"2024-10-06T09:27:20","guid":{"rendered":"https:\/\/server.hk\/cnblog\/44688\/"},"modified":"2024-10-06T17:27:20","modified_gmt":"2024-10-06T09:27:20","slug":"linux-%e5%91%bd%e4%bb%a4%ef%bc%9aexpr-%e8%a8%88%e7%ae%97%e8%a1%a8%e9%81%94%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/44688\/","title":{"rendered":"Linux \u547d\u4ee4\uff1aexpr &#8211; \u8a08\u7b97\u8868\u9054\u5f0f"},"content":{"rendered":"<h1 id=\"linux-%e5%91%bd%e4%bb%a4%ef%bc%9aexpr-%e8%a8%88%e7%ae%97%e8%a1%a8%e9%81%94%e5%bc%8f-gYOzymYarg\">Linux \u547d\u4ee4\uff1aexpr &#8211; \u8a08\u7b97\u8868\u9054\u5f0f<\/h1>\n<p>\u5728 Linux \u74b0\u5883\u4e2d\uff0c\u547d\u4ee4\u884c\u5de5\u5177\u662f\u9032\u884c\u5404\u7a2e\u64cd\u4f5c\u7684\u91cd\u8981\u624b\u6bb5\u3002\u5176\u4e2d\uff0c<code>expr<\/code> \u547d\u4ee4\u662f\u4e00\u500b\u7528\u65bc\u8a08\u7b97\u8868\u9054\u5f0f\u7684\u5de5\u5177\uff0c\u80fd\u5920\u57f7\u884c\u57fa\u672c\u7684\u6578\u5b78\u904b\u7b97\u3001\u5b57\u7b26\u4e32\u64cd\u4f5c\u548c\u908f\u8f2f\u904b\u7b97\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0e <code>expr<\/code> \u7684\u7528\u6cd5\u53ca\u5176\u5728\u65e5\u5e38\u5de5\u4f5c\u4e2d\u7684\u61c9\u7528\u3002<\/p>\n<h2 id=\"%e4%bb%80%e9%ba%bc%e6%98%af-expr%ef%bc%9f-gYOzymYarg\">\u4ec0\u9ebc\u662f expr\uff1f<\/h2>\n<p><code>expr<\/code> \u662f\u4e00\u500b\u7528\u65bc\u8a08\u7b97\u8868\u9054\u5f0f\u7684\u547d\u4ee4\u884c\u5de5\u5177\uff0c\u6700\u65e9\u51fa\u73fe\u5728 Unix \u7cfb\u7d71\u4e2d\u3002\u5b83\u53ef\u4ee5\u7528\u4f86\u9032\u884c\u6574\u6578\u904b\u7b97\u3001\u5b57\u7b26\u4e32\u9577\u5ea6\u8a08\u7b97\u3001\u5b57\u7b26\u4e32\u9023\u63a5\u7b49\u64cd\u4f5c\u3002<code>expr<\/code> \u7684\u57fa\u672c\u8a9e\u6cd5\u5982\u4e0b\uff1a<\/p>\n<pre><code>expr [\u904b\u7b97\u5f0f]<\/code><\/pre>\n<p>\u5728\u9019\u88e1\uff0c\u904b\u7b97\u5f0f\u53ef\u4ee5\u662f\u6578\u5b57\u3001\u5b57\u7b26\u4e32\u6216\u5176\u4ed6\u8868\u9054\u5f0f\u3002\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c<code>expr<\/code> \u5728\u8655\u7406\u904b\u7b97\u6642\uff0c\u5fc5\u9808\u4f7f\u7528\u7a7a\u683c\u4f86\u5206\u9694\u904b\u7b97\u7b26\u548c\u64cd\u4f5c\u6578\u3002<\/p>\n<h2 id=\"%e5%9f%ba%e6%9c%ac%e6%95%b8%e5%ad%b8%e9%81%8b%e7%ae%97-gYOzymYarg\">\u57fa\u672c\u6578\u5b78\u904b\u7b97<\/h2>\n<p>\u4f7f\u7528 <code>expr<\/code> \u9032\u884c\u57fa\u672c\u7684\u6578\u5b78\u904b\u7b97\u975e\u5e38\u7c21\u55ae\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u904b\u7b97\u793a\u4f8b\uff1a<\/p>\n<ul>\n<li><strong>\u52a0\u6cd5\uff1a<\/strong> <code>expr 5 + 3<\/code> \u6703\u8fd4\u56de 8\u3002<\/li>\n<li><strong>\u6e1b\u6cd5\uff1a<\/strong> <code>expr 10 - 4<\/code> \u6703\u8fd4\u56de 6\u3002<\/li>\n<li><strong>\u4e58\u6cd5\uff1a<\/strong> <code>expr 7 * 2<\/code> \u6703\u8fd4\u56de 14\u3002\u6ce8\u610f\uff0c\u4e58\u6cd5\u904b\u7b97\u7b26\u9700\u8981\u7528\u53cd\u659c\u6760\u8f49\u7fa9\u3002<\/li>\n<li><strong>\u9664\u6cd5\uff1a<\/strong> <code>expr 20 \/ 4<\/code> \u6703\u8fd4\u56de 5\u3002<\/li>\n<li><strong>\u53d6\u9918\u6578\uff1a<\/strong> <code>expr 10 % 3<\/code> \u6703\u8fd4\u56de 1\u3002<\/li>\n<\/ul>\n<h2 id=\"%e5%ad%97%e7%ac%a6%e4%b8%b2%e6%93%8d%e4%bd%9c-gYOzymYarg\">\u5b57\u7b26\u4e32\u64cd\u4f5c<\/h2>\n<p>\u9664\u4e86\u6578\u5b78\u904b\u7b97\uff0c<code>expr<\/code> \u9084\u53ef\u4ee5\u7528\u4f86\u9032\u884c\u5b57\u7b26\u4e32\u64cd\u4f5c\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u5e38\u898b\u7684\u5b57\u7b26\u4e32\u64cd\u4f5c\u793a\u4f8b\uff1a<\/p>\n<ul>\n<li><strong>\u5b57\u7b26\u4e32\u9577\u5ea6\uff1a<\/strong> <code>expr length \"Hello\"<\/code> \u6703\u8fd4\u56de 5\u3002<\/li>\n<li><strong>\u5b57\u7b26\u4e32\u9023\u63a5\uff1a<\/strong> <code>expr \"Hello\" : \"H.*\"<\/code> \u6703\u8fd4\u56de 5\uff0c\u9019\u88e1\u7684\u904b\u7b97\u662f\u5339\u914d\u5b57\u7b26\u4e32\u7684\u9577\u5ea6\u3002<\/li>\n<\/ul>\n<h2 id=\"%e9%82%8f%e8%bc%af%e9%81%8b%e7%ae%97-gYOzymYarg\">\u908f\u8f2f\u904b\u7b97<\/h2>\n<p><code>expr<\/code> \u9084\u652f\u6301\u908f\u8f2f\u904b\u7b97\uff0c\u9019\u5c0d\u65bc\u689d\u4ef6\u5224\u65b7\u975e\u5e38\u6709\u7528\u3002\u4ee5\u4e0b\u662f\u4e00\u4e9b\u908f\u8f2f\u904b\u7b97\u7684\u793a\u4f8b\uff1a<\/p>\n<ul>\n<li><strong>\u7b49\u65bc\uff1a<\/strong> <code>expr 5 = 5<\/code> \u6703\u8fd4\u56de 1\uff08\u771f\uff09\uff0c\u800c <code>expr 5 = 3<\/code> \u6703\u8fd4\u56de 0\uff08\u5047\uff09\u3002<\/li>\n<li><strong>\u4e0d\u7b49\u65bc\uff1a<\/strong> <code>expr 5 != 3<\/code> \u6703\u8fd4\u56de 1\uff08\u771f\uff09\u3002<\/li>\n<\/ul>\n<h2 id=\"%e4%bd%bf%e7%94%a8%e7%af%84%e4%be%8b-gYOzymYarg\">\u4f7f\u7528\u7bc4\u4f8b<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u4f7f\u7528 <code>expr<\/code> \u7684\u7c21\u55ae\u8173\u672c\u7bc4\u4f8b\uff0c\u8a72\u8173\u672c\u8a08\u7b97\u5169\u500b\u6578\u5b57\u7684\u548c\u3001\u5dee\u3001\u7a4d\u548c\u5546\uff1a<\/p>\n<pre><code>#!\/bin\/bash\necho \"\u8acb\u8f38\u5165\u7b2c\u4e00\u500b\u6578\u5b57\uff1a\"\nread num1\necho \"\u8acb\u8f38\u5165\u7b2c\u4e8c\u500b\u6578\u5b57\uff1a\"\nread num2\n\nsum=$(expr $num1 + $num2)\ndiff=$(expr $num1 - $num2)\nprod=$(expr $num1 * $num2)\nquot=$(expr $num1 \/ $num2)\n\necho \"\u548c\uff1a$sum\"\necho \"\u5dee\uff1a$diff\"\necho \"\u7a4d\uff1a$prod\"\necho \"\u5546\uff1a$quot\"\n<\/code><\/pre>\n<p>\u9019\u6bb5\u8173\u672c\u9996\u5148\u63d0\u793a\u7528\u6236\u8f38\u5165\u5169\u500b\u6578\u5b57\uff0c\u7136\u5f8c\u8a08\u7b97\u4e26\u986f\u793a\u5b83\u5011\u7684\u548c\u3001\u5dee\u3001\u7a4d\u548c\u5546\u3002<\/p>\n<h2 id=\"%e7%b8%bd%e7%b5%90-gYOzymYarg\">\u7e3d\u7d50<\/h2>\n<p>\u5728 Linux \u74b0\u5883\u4e2d\uff0c<code>expr<\/code> \u662f\u4e00\u500b\u5f37\u5927\u7684\u5de5\u5177\uff0c\u80fd\u5920\u5e6b\u52a9\u7528\u6236\u9032\u884c\u5404\u7a2e\u8a08\u7b97\u548c\u5b57\u7b26\u4e32\u64cd\u4f5c\u3002\u7121\u8ad6\u662f\u5728\u65e5\u5e38\u7684\u7cfb\u7d71\u7ba1\u7406\u9084\u662f\u8173\u672c\u7de8\u5beb\u4e2d\uff0c\u638c\u63e1 <code>expr<\/code> \u7684\u7528\u6cd5\u90fd\u80fd\u63d0\u9ad8\u5de5\u4f5c\u6548\u7387\u3002\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u7a69\u5b9a\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2f VPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\uff0c\u6eff\u8db3\u4e0d\u540c\u9700\u6c42\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4e86\u89e3 Linux \u547d\u4ee4 expr\uff0c\u8f15\u9b06\u8a08\u7b97\u6578\u5b78\u8868\u9054\u5f0f\uff0c\u652f\u6301\u52a0\u6e1b\u4e58\u9664\u904b\u7b97\uff0c\u63d0\u5347\u4f60\u7684\u547d\u4ee4\u884c\u6280\u80fd\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4924],"tags":[],"class_list":["post-44688","post","type-post","status-publish","format-standard","hentry","category-setup-tutorials"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/44688","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=44688"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/44688\/revisions"}],"predecessor-version":[{"id":44689,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/44688\/revisions\/44689"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=44688"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=44688"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=44688"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}