How to check if a file exists in Perl?

In this tutorial, we will take a couple of examples and demonstrate how you can if a file exists or not, with the help of Perl. Let's suppose we have a simple text file called "sample.txt" with the following data ?

This is a sample txt file
that contains some content inside it.
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We will use a Perl code to check whether this file exists or not.

Example 1

The most basic approach to check whether a file exists or not is to use the "-e" flag and then pass the name of the file. Consider the code shown below.

<div class="code-mirror  language-perl" contenteditable="plaintext-only" spellcheck="false" style="outline: none; overflow-wrap: break-word; overflow-y: auto; white-space: pre-wrap;"><span class="token keyword">use</span> warnings<span class="token punctuation">;</span>
<span class="token keyword">use</span> strict<span class="token punctuation">;</span>

<span class="token keyword">my</span> <span class="token variable">$filename</span> <span class="token operator">=</span> <span class="token string">'sample.txt'</span><span class="token punctuation">;</span>

<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">-e</span> <span class="token variable">$filename</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file exists\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file does not exist!\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</div>

Save the program code as "sample.pl" and then run the code using the following command ?

perl sample.pl

Example 2

We can also add more specific cases to check if a file contains any data, if it exists. In the following example, we will check both the cases, with minimum level of code. The "-s" flag in the code helps us in this regard.

<div class="code-mirror  language-perl" contenteditable="plaintext-only" spellcheck="false" style="outline: none; overflow-wrap: break-word; overflow-y: auto; white-space: pre-wrap;"><span class="token keyword">use</span> warnings<span class="token punctuation">;</span>
<span class="token keyword">use</span> strict<span class="token punctuation">;</span>

<span class="token keyword">my</span> <span class="token variable">$filename</span> <span class="token operator">=</span> <span class="token string">'sample.txt'</span><span class="token punctuation">;</span>

<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">-e</span> <span class="token variable">$filename</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file exists\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file does not exist!\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">-s</span> <span class="token variable">$filename</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file exists and contains some data inside it\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
   <span class="token keyword">print</span> <span class="token string">"the file exists but doesn't contain any data inside it\n"</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</div>

Again, save the file as "sample.pl" and run it using the following command

perl sample.pl

Conclusion

In addition to "-e" and "-s", there are other flags such as "-r" that checks if a file is readable, "-x" that checks if a file is executable, "-d" that checks if a file is a directory, etc. In this tutorial, we used two simple examples to show how you can use a Perl code to check if a file exists or not.