{"id":1420,"date":"2017-03-21T15:01:15","date_gmt":"2017-03-21T09:31:15","guid":{"rendered":"https:\/\/www.wikitechy.com\/technology\/?p=1420"},"modified":"2018-10-24T14:15:38","modified_gmt":"2018-10-24T08:45:38","slug":"double-dash-mean-also-known-bare-double-dash","status":"publish","type":"post","link":"https:\/\/www.wikitechy.com\/technology\/double-dash-mean-also-known-bare-double-dash\/","title":{"rendered":"What does \u201c&#8211;\u201d (double-dash) mean? (also known as \u201cbare double dash\u201d)"},"content":{"rendered":"<h2 id=\"double-dash\"><span style=\"color: #003300;\">Double dash:<\/span><\/h2>\n<ul>\n<li>The double dash \u201c\u2013\u201d means end of command line flags i.e. it tells the preceding command not to try to parse what comes after command line options.<\/li>\n<li>It is actually part of the POSIX standard that \u2014 can be used to separate options from other <a href=\"https:\/\/www.wikitechy.com\/technology\/how-to-pass-arguments-to-a-bash-script-using-linux\/\" target=\"_blank\" rel=\"noopener\">arguments<\/a>, so you will see it on <a href=\"https:\/\/www.wikitechy.com\/technology\/27-handy-chrome-os-commands-run-crosh\/\" target=\"_blank\" rel=\"noopener\">commands<\/a> like cp and mv (which are not part of Bash).<\/li>\n<li>\u2014 works to separate options from regular expressions in grep, but the canonical way is to use -e\/\u2013regexp<\/li>\n<\/ul>\n<h3 id=\"example-use\"><span style=\"color: #ff6600;\"><strong>Example use:<\/strong><\/span><\/h3>\n<p>you want to grep a file for the string -v \u2013 normally -v would be considered as the option to reverse the matching meaning (only show lines that do not match), but with \u2014 you can grep for string -v like this:<\/p>\n[pastacode lang=\u201dbash\u201d manual=\u201dgrep%20\u2013%20-v%20file%20\u2033 message=\u201dBash Code\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n<p>A\u00a0double dash\u00a0(\u00a0\u2014\u00a0) is used in <a href=\"https:\/\/www.wikitechy.com\/tutorials\/linux\/how-to-test-if-a-variable-is-a-number-in-bash\" target=\"_blank\" rel=\"noopener\">bash<\/a> built-in commands and there are more other commands to signify the end of command options, after which only positional parameters are accepted<\/p>\n<h3 id=\"example\"><span style=\"color: #808000;\"><strong>Example:<\/strong><\/span><\/h3>\n<p>Suppose you have a file named path\/to\/file.txt in my Git repository, and you want to revert changes on it.<\/p>\n[pastacode lang=\u201dbash\u201d manual=\u201dgit%20checkout%20path%2Fto%2Ffile.txt%0A\u201d message=\u201dBash Code\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n<p style=\"top: 214px;\">[ad type=\u201dbanner\u201d]\n<p>Now suppose that the file is named master\u2026<\/p>\n[pastacode lang=\u201dbash\u201d manual=\u201dgit%20checkout%20master%0A\u201d message=\u201dBash Code\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n<p>Whoops! That changed branches instead.\u00a0The \u2014 helps to separate the <a href=\"https:\/\/www.wikitechy.com\/technology\/c-algorithm-check-given-graph-tree-not\/\" target=\"_blank\" rel=\"noopener\">tree<\/a> you want to check out from the files you want to check out.<\/p>\n[pastacode lang=\u201dbash\u201d manual=\u201dgit%20checkout%20\u2013%20master%0A%0A\u201d message=\u201dBash Code\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n<h4 id=\"it-also-helps-us-if-some-freako-added-a-file-named-f-to-our-repository\"><span style=\"color: #ff6600;\"><b style=\"color: #ff6600;\">It also helps us if some <\/b><span style=\"color: #ff6600;\"><b>freako<\/b><\/span><b style=\"color: #ff6600;\">\u00a0added a file named -f to our repository:<\/b><\/span><\/h4>\n[pastacode lang=\u201dbash\u201d manual=\u201dgit%20checkout%20-f%20%20%20%20%20%20%23%20wrong%0Agit%20checkout%20\u2013%20-f%20%20%20%23%20right%0A\u201d message=\u201dBash Code\u201d highlight=\u201d\u201d provider=\u201dmanual\u201d\/]\n[ad type=\u201dbanner\u201d]\n","protected":false},"excerpt":{"rendered":"<p>Double dash: The double dash \u201c\u2013\u201d means end of command line flags i.e. it tells the preceding command not to try to parse what comes after command line options. It is actually part of the POSIX standard that \u2014 can be used to separate options from other arguments, so you will see it on commands [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1699,1331],"tags":[2765,2761,2755,2764,2756,2762,2758,2751,2763,2759,2752,2760,2753,2757,2754],"class_list":["post-1420","post","type-post","status-publish","format-standard","hentry","category-linux","category-unix","tag-bash-escape-double-dash","tag-bash-getopts-double-dash","tag-changing-extension-to-multiple-files","tag-double-hyphen-meaning","tag-how-to-less-a-file-named","tag-javascript-double-dash","tag-linux-dash-commands","tag-related-queries-what-is-dash-actually-in-unix-or-linux","tag-unix-command-line-options-convention","tag-unix-dash-commands","tag-what-does-mean-with-association-to-linux-files-and-directories","tag-what-does-the-double-dash-mean-in-writing","tag-why-do-many-cli-apps-take-a-single-argument","tag-why-do-we-use-double-dash-in-git-checkout","tag-why-is-printf-better-than-echo"],"_links":{"self":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/1420","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/comments?post=1420"}],"version-history":[{"count":0,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/posts\/1420\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/media?parent=1420"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/categories?post=1420"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wikitechy.com\/technology\/wp-json\/wp\/v2\/tags?post=1420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}