---
layout: page
category_title: interm
category-page: interm
tags: tee shell command
author: Nicola Brunner
title: tee
---

The <code>tee</code> command is used to split the output of a program, doing
this the output can be displayed in the shell and in the same time written in a
file. This is useful, for example, if we want to capture intermediate outputs of
a long program.
The command is named after the T-splitter used in plumbing, because they have
similar functions.<br>

<h3>Usage:</h3>
The default tee command syntax is:

<pre>
tee [flags] [file]
</pre>

Where <code>[flags]</code> are the tee flags (below you will find more info),
and argument <code>[file]</code> is a file or a list of files, each of which
receives the output.<br>

<h3>Flags:</h3>

<ul>
  <li><code>-a</code> Appends the output to each file, rather than overwriting it.</li>
  <li><code>-i</code> Ignores interrupt signals.</li>
</ul>

<h3>Example:</h3>

<pre>
date | tee example.txt
</pre>

With this example, we can see that tee writes the date in
<i>example.txt</i>, but shows also the output (in this case the date) in the shell.
If you would prefer to have content appended instead of overwritten on the file,
should use <code>-a</code> flag on <code>tee</code>.