Cat a File Without Comments

title:	Cat a File Without Comments
posted:	2023-02-22
tags:	["all", "linux", "shell", "regex"]

Technology keeps moving but this post has not.

What you're about to read hasn't been updated in more than a year. The information may be out of date. Let me know if you see anything that needs fixing.

It's super handy when a Linux config file is loaded with comments to tell you precisely how to configure the thing, but all those comments can really get in the way when you're trying to review the current configuration.

Next time, instead of scrolling through page after page of lengthy embedded explanations, just use:

egrep -v "^\s*(#|$)" $filename 
<span style="display:flex"><span>egrep -v <span style="color:#e6db74">"^\s*(#|</span><pre tabindex=0 style=color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4><code class=language-shell data-lang=shell><span style=display:flex><span>egrep -v <span style=color:#e6db74>"^\s*(#|</span>$<span style=color:#e6db74>)"</span> $filename <span style=color:#75715e># [tl! .cmd]</span>
</span></span></code></pre>lt;span style="color:#e6db74">)"</span> $filename <span style="color:#75715e"># [tl! .cmd]</span>
</span></span>

For added usefulness, I alias this command to ccat (which my brain interprets as "commentless cat") in my ~/.zshrc↗:

alias ccat='egrep -v "^\s*(#|$)"'
<span style="display:flex"><span>alias ccat<span style="color:#f92672">=</span><span style="color:#e6db74">'egrep -v "^\s*(#|$)"'</span>
</span></span>

Now instead of viewing all 75 lines of a mostly-default Vagrantfile, I just see the 7 that matter:

wc -l Vagrantfile 
75 Vagrantfile 
<span style="display:flex"><span>wc -l Vagrantfile <span style="color:#75715e"># [tl! .cmd]</span>
</span></span><span style="display:flex"><span><span style="color:#ae81ff">75</span> Vagrantfile <span style="color:#75715e"># [tl! .nocopy]</span>
</span></span>

ccat Vagrantfile 
Vagrant.configure("2") do |config| 
  config.vm.box = "oopsme/windows11-22h2"
  config.vm.provider :libvirt do |libvirt|
    libvirt.cpus = 4
    libvirt.memory = 4096
  end
end 
<span style="display:flex"><span>ccat Vagrantfile <span style="color:#75715e"># [tl! .cmd]</span>
</span></span><span style="display:flex"><span>Vagrant.configure<span style="color:#f92672">(</span><span style="color:#e6db74">"2"</span><span style="color:#f92672">)</span> <span style="color:#66d9ef">do</span> |config| <span style="color:#75715e"># [tl! .nocopy:start]</span>
</span></span><span style="display:flex"><span>  config.vm.box <span style="color:#f92672">=</span> <span style="color:#e6db74">"oopsme/windows11-22h2"</span>
</span></span><span style="display:flex"><span>  config.vm.provider :libvirt <span style="color:#66d9ef">do</span> |libvirt|
</span></span><span style="display:flex"><span>    libvirt.cpus <span style="color:#f92672">=</span> <span style="color:#ae81ff">4</span>
</span></span><span style="display:flex"><span>    libvirt.memory <span style="color:#f92672">=</span> <span style="color:#ae81ff">4096</span>
</span></span><span style="display:flex"><span>  end
</span></span><span style="display:flex"><span>end <span style="color:#75715e"># [tl! .nocopy:end]</span>
</span></span>

ccat Vagrantfile | wc -l 
7 
<span style="display:flex"><span>ccat Vagrantfile | wc -l <span style="color:#75715e"># [tl! .cmd]</span>
</span></span><span style="display:flex"><span><span style="color:#ae81ff">7</span> <span style="color:#75715e"># [tl! .nocopy]</span>
</span></span>

Nice!

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