commit: 187db88dfd631e9e10bc2e5e710f96a64d01e169 Author: Göktürk Yüksek <gokturk <AT> gentoo <DOT> org> AuthorDate: Sat Oct 29 16:27:05 2016 +0000 Commit: Göktürk Yüksek <gokturk <AT> gentoo <DOT> org> CommitDate: Mon Oct 31 01:09:00 2016 +0000 URL: https://gitweb.gentoo.org/proj/devmanual.git/commit/?id=187db88d
tools-reference/find: encourage the while read loop with '-print0' The "funky while read loop" has problems coping with file names containing special characters. Improve it by using the '-print0' option that uses the NUL character to delimit the output lines, which can be processed safely by the while read loop by adjusting the delimiter settings. As for whether supplying $'\0' is an undocumented feature or not, see: http://lists.gnu.org/archive/html/help-bash/2016-10/msg00039.html Suggested-By: David Seifert <soap <AT> gentoo.org> tools-reference/find/text.xml | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) diff --git a/tools-reference/find/text.xml b/tools-reference/find/text.xml index 4172128..8601a51 100644 --- a/tools-reference/find/text.xml +++ b/tools-reference/find/text.xml @@ -112,6 +112,15 @@ Useful rules include: </ti> <ti>no, GNU and FBSD</ti> </tr> + <tr> + <ti><c>-print0</c></ti> + <ti> + Separate file names by a NUL character instead of a newline in + the output. This is useful for guarding against files which may + include a newline in their names. + </ti> + <ti>no, GNU and FBSD</ti> + </tr> </table> <note> @@ -121,30 +130,30 @@ ebuild context for those EAPIs. <p> By default, <c>find</c> will echo a list of matching files to the -standard output. This can be used in a <c>while</c> loop: +standard output separated by newlines. It can be combined with a +<c>for</c> loop for a small number of files with no weird characters +and spaces in their names: </p> <codesample lang="ebuild"> -while read f ; do +for f in $(find "${S}" -type f) ; do einfo "Doing unholy things to ${f}" -done < <(find "${S}" -type f) +done </codesample> <p> -Or a <c>for</c> loop (for small numbers of files): +The above loop may cause issues with files containing special +characters in their names. A better way is to run <c>find</c> with the +<c>-print0</c> option in a <c>while</c> loop (note the options passed +to <c>while</c> and <c>read</c> for changing the delimiter): </p> <codesample lang="ebuild"> -for f in $(find "${S}" -type f) ; do +while IFS="" read -d $'\0' -r f ; do einfo "Calling down holy vengance upon ${f}" -done +done < <(find "${S}" -type f -print0) </codesample> -<warning> -In both cases, files with weird characters or spaces in their names -may cause serious problems. -</warning> - <p> As an alternative you can use the <c>-exec</c> argument. Be careful with escaping to ensure that <c>bash</c> doesn't gobble up the special
