{"id":162284,"date":"2019-11-20T10:00:29","date_gmt":"2019-11-20T02:00:29","guid":{"rendered":"https:\/\/lrxjmw.cn\/?p=162284"},"modified":"2019-10-23T14:59:15","modified_gmt":"2019-10-23T06:59:15","slug":"shell-string-operator","status":"publish","type":"post","link":"https:\/\/lrxjmw.cn\/shell-string-operator.html","title":{"rendered":"Shell\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26"},"content":{"rendered":"<table>\n<tbody>\n<tr>\n<td style=\"padding: 5px 12px; width: 25px; font-size: 22px; text-align: center; background: #E8E8E8; line-height: 30px; color: #999;\">\u5bfc\u8bfb<\/td>\n<td style=\"padding: 10px 10px 12px; line-height: 20px;\"><strong>\u8fd0\u7b97\u7b26\u4e0e\u5de6\u53f3\u7684\u5b57\u7b26\u4e32\u4e4b\u95f4\u5fc5\u987b\u7528\u7a7a\u683c\u9694\u5f00\uff0c\u5373\u4f7f\u5de6\u8fb9\u6ca1\u6709\u5b57\u7b26\u4e32\u5982\u6587\u4ef6\u6d4b\u8bd5\u8fd0\u7b97\u7b26\u4e5f\u9700\u8981\u6709\u7a7a\u683c\u9694\u5f00<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter  wp-image-162286\" src=\"https:\/\/lrxjmw.cn\/wp-content\/uploads\/2019\/10\/4-8.jpg\" alt=\"\" width=\"593\" height=\"333\" srcset=\"https:\/\/lrxjmw.cn\/wp-content\/uploads\/2019\/10\/4-8.jpg 341w, https:\/\/lrxjmw.cn\/wp-content\/uploads\/2019\/10\/4-8-300x168.jpg 300w\" sizes=\"auto, (max-width: 593px) 100vw, 593px\" \/><\/p>\n<p><strong>\u4e0b\u9762\u5217\u51fa\u4e86\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26\uff0c\u5047\u5b9a\u53d8\u91cf a \u4e3a \"abc\"\uff0c\u53d8\u91cf b \u4e3a \"efg\"\uff1a<\/strong><\/p>\n<table class=\"reference\">\n<tbody>\n<tr>\n<th>\n\t\t\t\t\u8fd0\u7b97\u7b26<\/th>\n<th>\n\t\t\t\t\u8bf4\u660e<\/th>\n<th>\n\t\t\t\t\u4e3e\u4f8b<\/th>\n<\/tr>\n<tr>\n<td>\n\t\t\t\t=<\/td>\n<td>\n\t\t\t\t\u68c0\u6d4b\u4e24\u4e2a\u5b57\u7b26\u4e32\u662f\u5426\u76f8\u7b49\uff0c\u76f8\u7b49\u8fd4\u56de true\u3002<\/td>\n<td>\n\t\t\t\t[ $a = $b ] \u8fd4\u56de false\u3002<\/td>\n<\/tr>\n<tr>\n<td>\n\t\t\t\t!=<\/td>\n<td>\n\t\t\t\t\u68c0\u6d4b\u4e24\u4e2a\u5b57\u7b26\u4e32\u662f\u5426\u76f8\u7b49\uff0c\u4e0d\u76f8\u7b49\u8fd4\u56de true\u3002<\/td>\n<td>\n\t\t\t\t[ $a != $b ] \u8fd4\u56de&nbsp;true\u3002<\/td>\n<\/tr>\n<tr>\n<td>\n\t\t\t\t-z<\/td>\n<td>\n\t\t\t\t\u68c0\u6d4b\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u5426\u4e3a0\uff0c\u4e3a0\u8fd4\u56de true\u3002<\/td>\n<td>\n\t\t\t\t[ -z $a ] \u8fd4\u56de false\u3002<\/td>\n<\/tr>\n<tr>\n<td>\n\t\t\t\t-n<\/td>\n<td>\n\t\t\t\t\u68c0\u6d4b\u5b57\u7b26\u4e32\u957f\u5ea6\u662f\u5426\u4e3a0\uff0c\u4e0d\u4e3a0\u8fd4\u56de true\u3002<\/td>\n<td>\n\t\t\t\t[ -n \"$a\" ] \u8fd4\u56de true\u3002<\/td>\n<\/tr>\n<tr>\n<td>\n\t\t\t\t$<\/td>\n<td>\n\t\t\t\t\u68c0\u6d4b\u5b57\u7b26\u4e32\u662f\u5426\u4e3a\u7a7a\uff0c\u4e0d\u4e3a\u7a7a\u8fd4\u56de true\u3002<\/td>\n<td>\n\t\t\t\t[ $a ] \u8fd4\u56de&nbsp;true\u3002<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><strong>\u5b9e\u4f8b<\/strong><\/p>\n<p>\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26\u5b9e\u4f8b\u5982\u4e0b\uff1a<\/p>\n<pre>\u5b9e\u4f8b\r\n\r\n#!\/bin\/bash\r\n# author:\u83dc\u9e1f\u6559\u7a0b\r\n# url:www.runoob.com\r\n\r\na=\"abc\"\r\nb=\"efg\"\r\n\r\nif [ $a = $b ]\r\nthen\r\n   echo \"$a = $b : a \u7b49\u4e8e b\"\r\nelse\r\n   echo \"$a = $b: a \u4e0d\u7b49\u4e8e b\"\r\nfi\r\nif [ $a != $b ]\r\nthen\r\n   echo \"$a != $b : a \u4e0d\u7b49\u4e8e b\"\r\nelse\r\n   echo \"$a != $b: a \u7b49\u4e8e b\"\r\nfi\r\nif [ -z $a ]\r\nthen\r\n   echo \"-z $a : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e3a 0\"\r\nelse\r\n   echo \"-z $a : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e0d\u4e3a 0\"\r\nfi\r\nif [ -n \"$a\" ]\r\nthen\r\n   echo \"-n $a : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e0d\u4e3a 0\"\r\nelse\r\n   echo \"-n $a : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e3a 0\"\r\nfi\r\nif [ $a ]\r\nthen\r\n   echo \"$a : \u5b57\u7b26\u4e32\u4e0d\u4e3a\u7a7a\"\r\nelse\r\n   echo \"$a : \u5b57\u7b26\u4e32\u4e3a\u7a7a\"\r\nfi<\/pre>\n<p>\u6267\u884c\u811a\u672c\uff0c\u8f93\u51fa\u7ed3\u679c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n<pre>abc = efg: a \u4e0d\u7b49\u4e8e b\r\nabc != efg : a \u4e0d\u7b49\u4e8e b\r\n-z abc : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e0d\u4e3a 0\r\n-n abc : \u5b57\u7b26\u4e32\u957f\u5ea6\u4e0d\u4e3a 0\r\nabc : \u5b57\u7b26\u4e32\u4e0d\u4e3a\u7a7a<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u4e0b\u9762\u5217\u51fa\u4e86\u5e38\u7528\u7684\u5b57\u7b26\u4e32\u8fd0\u7b97\u7b26\uff0c\u5047\u5b9a\u53d8\u91cf a \u4e3a &#8220;abc&#8221;\uff0c\u53d8\u91cf b \u4e3a &#8220;efg&#8221;\uff1a \u8fd0\u7b97\u7b26 \u8bf4\u660e \u4e3e\u4f8b = [&hellip;]<\/p>\n","protected":false},"author":321,"featured_media":162285,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[55],"tags":[],"class_list":["post-162284","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-thread"],"acf":[],"_links":{"self":[{"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/posts\/162284","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/users\/321"}],"replies":[{"embeddable":true,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/comments?post=162284"}],"version-history":[{"count":3,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/posts\/162284\/revisions"}],"predecessor-version":[{"id":162289,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/posts\/162284\/revisions\/162289"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/media\/162285"}],"wp:attachment":[{"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/media?parent=162284"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/categories?post=162284"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lrxjmw.cn\/wp-json\/wp\/v2\/tags?post=162284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}