{"id":2253,"date":"2013-01-15T22:37:48","date_gmt":"2013-01-15T14:37:48","guid":{"rendered":"http:\/\/blog.pighead.cc\/whsyu\/?p=2253"},"modified":"2013-02-08T23:03:16","modified_gmt":"2013-02-08T15:03:16","slug":"set-default-value-of-variable","status":"publish","type":"post","link":"https:\/\/blog.pighead.cc\/whsyu\/2013\/01\/15\/set-default-value-of-variable\/","title":{"rendered":"shell script \u8b8a\u6578\u7684\u9810\u8a2d\u503c"},"content":{"rendered":"<p class=\"bb-post-separator\"><strong>[\u5ba2\u5bb6\u8a71, hak-Hant-TW]  <\/strong><\/p><p>\u6709\u9019\u7a2e\u9700\u8981\uff0c\u5c0b\u4e00\u4e0b\u7db2\u8def\u770b\u5230<a href=\"http:\/\/www.cyberciti.biz\/faq\/bash-ksh-if-variable-is-not-defined-set-default-variable\/\">\u9019\u7bc7<\/a>\u6709\u5beb\uff0c\u8a66\u636f\u6bcb\u6703\u9ebb\u7169\uff0c\u8a18\u4e00\u4e0b\u3002<\/p>\n<pre lang=\"bash\">#!\/bin\/sh\r\n$DEFAULT_VAR=\"VALUE\"\r\nVAR=\"${VAR-$DEFAULT_VAR}\"<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>[\u5ba2\u5bb6\u8a71, hak-Hant-TW] \u6709\u9019\u7a2e\u9700\u8981\uff0c\u5c0b\u4e00\u4e0b\u7db2\u8def\u770b\u5230\u9019\u7bc7\u6709\u5beb\uff0c\u8a66\u636f\u6bcb\u6703\u9ebb\u7169\uff0c\u8a18\u4e00\u4e0b\u3002 #!\/bin\/sh $DEFAULT_VAR=&#8221;VALUE&#8221; VAR=&#8221;${VAR-$DEFAULT_VAR}&#8221;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[4271],"class_list":["post-2253","post","type-post","status-publish","format-standard","hentry","category-freebsd","tag-shell-scripts"],"_links":{"self":[{"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/posts\/2253","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/comments?post=2253"}],"version-history":[{"count":5,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/posts\/2253\/revisions"}],"predecessor-version":[{"id":2258,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/posts\/2253\/revisions\/2258"}],"wp:attachment":[{"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/media?parent=2253"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/categories?post=2253"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.pighead.cc\/whsyu\/wp-json\/wp\/v2\/tags?post=2253"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}