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It is very good. Thank you very much
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in the following code, why $SHELL and *.c will not be expanded by Unix shell?<br />
<br />
int main()<br />
{ if (fork()==0)<br />
&nbsp; &nbsp; &nbsp; execlp(&quot;echo&quot;,&quot;echo&quot;,&quot;$SHE<wbr />LL&quot;,NULL);<wbr /><br />
&nbsp; else &nbsp; <br />
&nbsp; &nbsp; &nbsp; execlp(&quot;echo&quot;,&quot;echo&quot;,&quot;*.c&quot;<wbr />,NULL);<br />
}
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in the following code, why $SHELL and *.c will not be expanded by Unix shell?

int main()
{ if (fork()==0)
      execlp("echo","echo","$SHELL",NULL);
  else   
      execlp("echo","echo","*.c",NULL);
}

execlp(&quot;echo&quot;,&quot;echo&quot;,&quot;$SHELL&quot;,NULL&quot;)

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. By design, C provides constructs that map efficiently to typical machine instructions, so it has found lasting use in applications that had formerly been coded in assembly language, including operating systems as well as various application software for computers ranging from supercomputers to embedded systems. It is distinct from C++ (which has its roots in C) and C#, and many later languages have borrowed directly or indirectly from C.

execlp(&quot;echo&quot;,&quot;echo&quot;,&quot;$SHELL&quot;,NULL&quot;)

execlp("echo","echo","$SHELL",NULL")