xcode-file-redirection.md

+What is it?
+--------
+[I/O Redirection](http://www.tldp.org/LDP/abs/html/io-redirection.html) is a powerful tool that allows the shell to either simulate keyboard input from a file (input redirection), capture all output in a file (output redirection), or both. Using redirection allows programs to use files for input and output using only `cin`, `cout`, and/or `cerr`, eliminating the need to explicitly handle files (`fopen()`) or input streams (`istream` or `ostream`).
+
+### Examples
+```
+% ./program < redirected-to-cin.txt
+% ./program > redirected-from-cout.txt
+% ./program > redirected-from-cout.txt 2> redirected-from-cerr.txt
+% ./program < redirected-to-cin.txt > redirected-from-cout.txt
+etc...
+```
+
+How to do it
+--------
+
+### Command-line Arguments (options, arguments and filenames)
+
+To specify command-line arguments in Xcode select from the menu Product -> Scheme -> Edit Scheme. Savvy users will use the keyboard shortcut Command+<. The arguments specified this way will be read and passed to your program in `argv[]`, which will allow you use `getopt()`, `getopt_long()`, or simply parse the arguments manually.
+
+### File Redirection
+
+Xcode will allow you specify command-line parameters, but no longer directly supports command-line style redirection. To provide your own support, you can use [`freopen()`](https://linux.die.net/man/3/freopen). This will let you open a file using a filename and associate it with a stream.
+
+#### Examples
+
+```C++
+int main() {
+    freopen("redirected-to-cin.txt", "r", stdin);  // Redirected input
+    freopen("redirected-from-cout.txt", "w", stdout);  // Redirected output
+    freopen("redirected-from-cerr.txt", "w", stderr);  // Redirected output
+    return 0;
+}
+```
+
+How to do it well
+--------
+
+### Conditional compilation
+
+### Using environment variables
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