After you installed `ccache`, it won't be enabled by default.

First, you need to determine who is allowed to use `ccache`. You have to
add each user to the `ccache` group. If you want to allow using `ccache`
from chrooted builds, then you need to add the `fst` user:

----
# usermod -a -G ccache fst
----

Second, you need to somehow let the build system to use `ccache`, and
not the compiler directly. If you use `makepkg`, this is enabled by
default (you can disable it with the `-B` option). If you build
manually, then you are on your own, though usually there are two ways to
do so:

- Tell the configure script to use a different compiler:

--------------------------------
$ CC=/usr/bin/ccache ./configure
--------------------------------

- Modify path to use the fake compiler provided by `ccache`:

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export PATH=/usr/lib/ccache/bin:$PATH
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