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<li><a class="reference internal" href="#">printf - display text according to a format string</a><ul>
<li><a class="reference internal" href="#synopsis">Synopsis</a></li>
<li><a class="reference internal" href="#description">Description</a></li>
<li><a class="reference internal" href="#format-specifiers">Format Specifiers</a></li>
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<section id="printf-display-text-according-to-a-format-string">
<h1>printf - display text according to a format string<a class="headerlink" href="#printf-display-text-according-to-a-format-string" title="Link to this heading">¶</a></h1>
<section id="synopsis">
<h2>Synopsis<a class="headerlink" href="#synopsis" title="Link to this heading">¶</a></h2>
<div class="highlight-fish-synopsis notranslate"><div class="highlight"><pre><span></span><span class="nf">printf</span><span class="w"> </span><span class="no">FORMAT</span><span class="w"> </span><span class="g g-Other">[</span><span class="no">ARGUMENT</span><span class="w"> </span><span class="g g-Other">...]</span>
</pre></div>
</div>
</section>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Link to this heading">¶</a></h2>
<p><code class="docutils literal notranslate"><span class="pre">printf</span></code> uses the format string <em>FORMAT</em> to print the <em>ARGUMENT</em> arguments. This means that it takes format specifiers in the format string and replaces each with an argument.</p>
<p>The <em>FORMAT</em> argument is re-used as many times as necessary to convert all of the given arguments. So <code class="docutils literal notranslate"><span class="pre">printf</span> <span class="pre">%s\n</span> <span class="pre">flounder</span> <span class="pre">catfish</span> <span class="pre">clownfish</span> <span class="pre">shark</span></code> will print four lines.</p>
<p>Unlike <a class="reference internal" href="echo.html"><span class="doc">echo</span></a>, <code class="docutils literal notranslate"><span class="pre">printf</span></code> does not append a new line unless it is specified as part of the string.</p>
<p>It doesn’t support any options, so there is no need for a <code class="docutils literal notranslate"><span class="pre">--</span></code> separator, which makes it easier to use for arbitrary input than <code class="docutils literal notranslate"><span class="pre">echo</span></code>. <a class="footnote-reference brackets" href="#id2" id="id1" role="doc-noteref"><span class="fn-bracket">[</span>1<span class="fn-bracket">]</span></a></p>
</section>
<section id="format-specifiers">
<h2>Format Specifiers<a class="headerlink" href="#format-specifiers" title="Link to this heading">¶</a></h2>
<p>Valid format specifiers are taken from the C library function <code class="docutils literal notranslate"><span class="pre">printf(3)</span></code>:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">%d</span></code> or <code class="docutils literal notranslate"><span class="pre">%i</span></code>: Argument will be used as decimal integer (signed or unsigned)</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%o</span></code>: An octal unsigned integer</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%u</span></code>: An unsigned decimal integer - this means negative numbers will wrap around</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%x</span></code> or <code class="docutils literal notranslate"><span class="pre">%X</span></code>: An unsigned hexadecimal integer</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%f</span></code>, <code class="docutils literal notranslate"><span class="pre">%g</span></code> or <code class="docutils literal notranslate"><span class="pre">%G</span></code>: A floating-point number. <code class="docutils literal notranslate"><span class="pre">%f</span></code> defaults to 6 places after the decimal point (which is locale-dependent - e.g. in de_DE it will be a <code class="docutils literal notranslate"><span class="pre">,</span></code>). <code class="docutils literal notranslate"><span class="pre">%g</span></code> and <code class="docutils literal notranslate"><span class="pre">%G</span></code> will trim trailing zeroes and switch to scientific notation (like <code class="docutils literal notranslate"><span class="pre">%e</span></code>) if the numbers get small or large enough.</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%e</span></code> or <code class="docutils literal notranslate"><span class="pre">%E</span></code>: A floating-point number in scientific (XXXeYY) notation</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%s</span></code>: A string</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">%b</span></code>: As a string, interpreting backslash escapes, except that octal escapes are of the form 0 or 0ooo.</p></li>
</ul>
<p><code class="docutils literal notranslate"><span class="pre">%%</span></code> signifies a literal “%”.</p>
<p>Conversion can fail, e.g. “102.234” can’t losslessly convert to an integer, causing printf to print an error. If you are okay with losing information, silence errors with <code class="docutils literal notranslate"><span class="pre">2>/dev/null</span></code>.</p>
<p>A number between the <code class="docutils literal notranslate"><span class="pre">%</span></code> and the format letter specifies the width. The result will be left-padded with spaces.</p>
</section>
<section id="backslash-escapes">
<h2>Backslash Escapes<a class="headerlink" href="#backslash-escapes" title="Link to this heading">¶</a></h2>
<p>printf also knows a number of backslash escapes:</p>
<ul class="simple">
<li><p><code class="docutils literal notranslate"><span class="pre">\"</span></code> double quote</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\\</span></code> backslash</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\a</span></code> alert (bell)</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\b</span></code> backspace</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\c</span></code> produce no further output</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\e</span></code> escape</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\f</span></code> form feed</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\n</span></code> new line</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\r</span></code> carriage return</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\t</span></code> horizontal tab</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\v</span></code> vertical tab</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\ooo</span></code> octal number (ooo is 1 to 3 digits)</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\xhh</span></code> hexadecimal number (hhh is 1 to 2 digits)</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\uhhhh</span></code> 16-bit Unicode character (hhhh is 4 digits)</p></li>
<li><p><code class="docutils literal notranslate"><span class="pre">\Uhhhhhhhh</span></code> 32-bit Unicode character (hhhhhhhh is 8 digits)</p></li>
</ul>
</section>
<section id="errors-and-return-status">
<h2>Errors and Return Status<a class="headerlink" href="#errors-and-return-status" title="Link to this heading">¶</a></h2>
<p>If the given argument doesn’t work for the given format (like when you try to convert a number like 3.141592 to an integer), printf prints an error, to stderr. printf will then also return non-zero, but will still try to print as much as it can.</p>
<p>It will also return non-zero if no argument at all was given, in which case it will print nothing.</p>
<p>This printf has been imported from the printf in GNU Coreutils version 6.9. If you would like to use a newer version of printf, for example the one shipped with your OS, try <code class="docutils literal notranslate"><span class="pre">command</span> <span class="pre">printf</span></code>.</p>
</section>
<section id="example">
<h2>Example<a class="headerlink" href="#example" title="Link to this heading">¶</a></h2>
<div class="highlight-fish-docs-samples notranslate"><div class="highlight"><pre><span></span><span class="nf">printf</span><span class="w"> </span><span class="s1">'%s\t%s\n'</span><span class="w"> </span><span class="no">flounder</span><span class="w"> </span><span class="no">fish</span>
</pre></div>
</div>
<p>Will print “flounder fish” (separated with a tab character), followed by a newline character. This is useful for writing completions, as fish expects completion scripts to output the option followed by the description, separated with a tab character.</p>
<div class="highlight-fish-docs-samples notranslate"><div class="highlight"><pre><span></span><span class="nf">printf</span><span class="w"> </span><span class="s1">'%s: %d'</span><span class="w"> </span><span class="s2">"Number of bananas in my pocket"</span><span class="w"> </span><span class="no">42</span>
</pre></div>
</div>
<p>Will print “Number of bananas in my pocket: 42”, <cite>without</cite> a newline.</p>
</section>
<section id="see-also">
<h2>See Also<a class="headerlink" href="#see-also" title="Link to this heading">¶</a></h2>
<ul class="simple">
<li><p>the <a class="reference internal" href="echo.html"><span class="doc">echo</span></a> command, for simpler output</p></li>
</ul>
</section>
<section id="footnotes">
<h2>Footnotes<a class="headerlink" href="#footnotes" title="Link to this heading">¶</a></h2>
<aside class="footnote-list brackets">
<aside class="footnote brackets" id="id2" role="doc-footnote">
<span class="label"><span class="fn-bracket">[</span><a role="doc-backlink" href="#id1">1</a><span class="fn-bracket">]</span></span>
<p>In fact, while fish’s <code class="docutils literal notranslate"><span class="pre">echo</span></code> supports <code class="docutils literal notranslate"><span class="pre">--</span></code>, POSIX forbids it, so other implementations can’t be used if the input contains anything starting with <code class="docutils literal notranslate"><span class="pre">-</span></code>.</p>
</aside>
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