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[bug #39824] Add suggestion 'ls | tr \\n \\0 | xargs -0 command' to xarg


From: James Youngman
Subject: [bug #39824] Add suggestion 'ls | tr \\n \\0 | xargs -0 command' to xargs man page
Date: Sun, 12 Jan 2014 20:47:28 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36

Update of bug #39824 (project findutils):

                  Status:                    None => Works For Me           
             Open/Closed:                    Open => Closed                 
                 Summary: Add suggestion 'ls | tr \\n \\0 | xargs -0 command'
to xargs man page => Add suggestion 'ls | tr \n \0 | xargs -0 command' to
xargs man page

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Follow-up Comment #4:

As you point out 

find ... -print0 | tr \\n\\0 \\1\\n | grep ... | tr \\1\\n \\n\\0 | xargs -0,

is cumbersome.  But it's also pointless since find has -regex.

There are plenty of misconceptions about Unix filenames.   One of them, as you
point out, is that they don't/can't contain blanks.  Of course, they can.  
But a much more pervasive misapprehension is that file names are text.  They
are not; instead they are byte sequences, in which system calls consider '/'
to be special, and which are terminated by \0 when presented to the API.

The critical difference is that nothing on a Unix system requires or enforces
that a directory name has the same character encoding as its parent.   So
there is no single locale configuration which will allow one to correctly
process a general path name as text.   This includes the "C" locale (as a
trivial example, it fails to correctly collate characters beyond <DEL>).  For
this reason processing path names with grep or sed, while common and popular,
is probably never going to be without problems, though I suppose one could
invent a kind of they're-just-bytes locale definition.

Anyway, because this kind of use of tr perpetuates misunderstandings about
what bytes values can exist in file names and what they mean, I wouldn't
really want to include a "tr" command acting on file names in the
documentation, except perhaps as a cautionary example.


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