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<!--replace-end-7--><!--replace-end-4--><!--replace-end-1--></head><body><div class="ui fluid container universe"><!--replace-start-2--><!--replace-start-3--><!--replace-start-6--><div class="ui text container" id="zettel-container" style="position: relative"><div class="zettel-view"><article class="ui raised attached segment zettel-content"><div class="pandoc"><h1 id="title-h1">File descriptors</h1><p>File descriptors are shorthand for <code>stdin</code>, <code>stdout</code> and <code>stderr</code>:</p><table class="ui table"><thead><tr><th>File descriptor</th><th>Name</th><th>Common abbreviation</th></tr></thead><tbody><tr><td>0</td><td>Standard input</td><td><code>stdin</code></td></tr><tr><td>1</td><td>Standard output</td><td><code>stdout</code></td></tr><tr><td>2</td><td>Standard error</td><td><code>stderr</code></td></tr></tbody></table><p>They are typically used when you want to <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Redirection"><a href="Redirection_in_Bash.html">redirect</a></span></span> the output of the standard/input /output/error somewhere, e.g a file or as input to another program. A classic case is <code>[some_command] > /dev/null 2>&1</code></p><p>They are all technically “files” which are open and which append themselves to every process that can run in the shell. For any command or program that you run, you will be able to access <code>0</code>, <code>1</code> and <code>2</code> for them. In this way they are similar to variables like <a href="Passing_arguments_and_options_to_Bash_scripts.md#passing-arguments"><code>$0</code></a> and <a href="Passing_arguments_and_options_to_Bash_scripts.md#passing-arguments"><code>$@</code></a>. They have a universal meaning within the context of the shell runtime.</p></div></article><nav class="ui attached segment deemphasized backlinksPane" id="neuron-backlinks-pane"><h3 class="ui header">Backlinks</h3><ul class="backlinks"><li><span class="zettel-link-container cf"><span class="zettel-link"><a href="Redirection_in_Bash.html">Redirection</a></span></span><ul class="context-list" style="zoom: 85%;"><li class="item"><div class="pandoc"><p>It is common practice to combine redirection with the <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: File descriptors"><a href="File_descriptors.html">file descriptors</a></span></span> to redirect the output of <code>stdout</code> and <code>stderr</code>. A common case is to <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Redirecting to /dev/null"><a href="Redirect_to_dev_null.html">redirect error output to <code>/dev/null</code></a></span></span>.</p></div></li></ul></li></ul></nav><nav class="ui attached segment deemphasized bottomPane" id="neuron-tags-pane"><div><span class="ui basic label zettel-tag" title="Tag">shell</span></div></nav><nav class="ui bottom attached icon compact inverted menu blue" id="neuron-nav-bar"><!--replace-start-9--><!--replace-end-9--><a class="right item" href="impulse.html" title="Open Impulse"><i class="wave square icon"></i></a></nav></div></div><!--replace-end-6--><!--replace-end-3--><!--replace-end-2--><div class="ui center aligned container footer-version"><div class="ui tiny image"><a href="https://neuron.zettel.page"><img alt="logo" src="https://raw.githubusercontent.com/srid/neuron/master/assets/neuron.svg" title="Generated by Neuron 1.9.35.3" /></a></div></div></div></body></html> |