Running Commands with exec()

exec() is one of many functions that enable you to pass commands to the shell. The function requires a string representing the path to the command you want to run. It also optionally accepts an array variable that is populated with the command’s output and a scalar variable that is populated with the command’s return value.

To get a listing for the current working directory, for example, you might pass exec() the command "ls -al .". We do this in Listing 21.4 (line 7), printing the result to the browser.

Listing 21.4. Using exec() to Produce a Directory Listing
 1: <!DOCTYPE html PUBLIC
 2:   "-//W3C//DTD XHTML 1.0 Strict//EN"
 3:   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 4: <html>
 5: <head>
 6: <title>Listing ...

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