====== Regex - File Types ======

<code bash>
^.*\.(jpg|JPG|gif|GIF|doc|DOC|pdf|PDF)$
</code>

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<code bash>
^.+\.(?:(?:[dD][oO][cC][xX]?)|(?:[pP][dD][fF]))$
</code>

<WRAP info>
**NOTE:** This will accept .doc, .docx, .pdf files having a filename of at least one character:

  * **^** - beginning of string.
  * **.+** - at least one character (any character).
  * **\.** - dot ('.').
  * **(?:pattern)** - match the pattern without storing the match).
  * **[dD]** - any character in the set ('d' or 'D').
  * **[xX]?** - any character in the set or none.
    *  **x** may be missing so 'doc' or 'docx' are both accepted.
  * **|** - either the previous or the next pattern.
  * **$** - end of matched string.

</WRAP>

<WRAP important>
**WARNING:**  Without enclosing the whole chain of extensions in **(?:)**, an extension like .docpdf would pass.
</WRAP>

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