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diff --git a/doc/howitworks.docbook b/doc/howitworks.docbook index abb25fb..4472531 100644 --- a/doc/howitworks.docbook +++ b/doc/howitworks.docbook @@ -144,6 +144,46 @@ in the next sections and chapters. </sect1> +<sect1 id="whitespaces"> +<title>Whitespaces handling and safety</title> + +<para> +While there are currently some limitations in ebuilds and in Portage +code that disallow using paths with spaces for important directories +like the merge root, the temporary directory and the portage tree +directory, autoepatch was supposed not to break even if all of them had +all kind of special characters. Unfortunately this is not always +possible, because of limitations in the tools and the language used. +</para> + +<para> +The biggest limitation is provided by bash itself: variables cannot +contain the NULL character, which means that the targets cannot be +passed with the output of find -print0 or grep -Z, so the targets +have to be separated by the \n sequence (new line). +</para> + +<para> +To try minimising the possibility of problems during piping throught +different commands (find, grep and so on), it is suggested to use the +option <emphasis>find $dir -exec cmd {} +</emphasis> rather than using +-print and xargs (this also avoids one process spawn), and if you need +to pass the result of grep -l, also add the --null parameter. +</para> + +<warning> + <para> + For reasons far from our understanding, FreeBSD people decided to + use the -Z option to GNU grep to support running grep over + gzip-compressed files. For compatibility and portability, rather + than using the -Z option, you should use the --null option in + autoepatch patchsets, which would behave consistently on both Linux + and non-Linux systems. + </para> +</warning> + +</sect1> + <sect1 id="prefixsupport"> <title>Alternative prefixes support</title> |