<p>I have never used octal numbers in my code nor come across any code that used it (hexadecimal and bit twiddling notwithstanding).</p>

<p>I started programming in C/C++ about 1994 so maybe I'm too young for this? Does older code use octal? C includes support for these by prepending a 0, but where is the code that uses these base 8 number literals?</p>

It's useful for the
```
chmod
```
and
```
mkdir
```
functions in Unix land, but aside from that I can't think of any other common uses.