□ Global variable that stores the cause of a error when a function is executed<br />
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□ Return value can only check whether an error occurred<br />
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□ If there is no error, 0 is stored. If there is a error, error code is stored<br />
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□ Error code is stored in the path /usr/include/asm/errno.h<br />
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□ #include&lt;errno.h&gt; is needed to use errno variable<br />
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It is also posted at : http://cysecguide.blogspot.com/2016/09/errno-variable.html