3.9. The `.ghci` file
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## 3.9. The `.ghci` file

When it starts, unless the `-ignore-dot-ghci` flag is given, GHCi reads and executes commands from `./.ghci`, followed by `$HOME/.ghci`.

The `.ghci` in your home directory is most useful for turning on favourite options (eg. `:set +s`), and defining useful macros. Placing a `.ghci` file in a directory with a Haskell project is a useful way to set certain project-wide options so you don't have to type them everytime you start GHCi: eg. if your project uses GHC extensions and CPP, and has source files in three subdirectories A, B and C, you might put the following lines in `.ghci`:

    :set -fglasgow-exts -cpp
    :set -iA:B:C

(Note that strictly speaking the `-i` flag is a static one, but in fact it works to set it using `:set` like this. The changes won't take effect until the next `:load`, though.)

Two command-line options control whether the `.ghci` files are read:

`-ignore-dot-ghci`

  Don't read either `./.ghci` or `$HOME/.ghci` when starting up.

`-read-dot-ghci`

  Read `.ghci` and `$HOME/.ghci`. This is normally the default, but the `-read-dot-ghci` option may be used to override a previous `-ignore-dot-ghci` option.

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