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Full Discussion: Newbie question: if[command not null]
Top Forums Shell Programming and Scripting Newbie question: if[command not null] Post 302513299 by alister on Tuesday 12th of April 2011 09:03:24 PM
Old 04-12-2011
Quote:
Originally Posted by Corona688
As it happens GNU find has the -print0 option to print nulls instead of newlines, and GNU xargs has the --null option to use nulls as separators.

If your argument is just that these arguments aren't portable, perhaps it's time to mandate them in POSIX.

There's always -exec, too, which will always be given a correct filename.
The find/xarg -print0/-0 tandem is useful but it's of no help when the output is coming from ls or stat or lsof or any one of countless tools which output filenames.

I do agree with you though that it would be useful for posix xargs to support some means of specifying a delimiter.

My argument is simply that traditional unix tools were designed to pipe text streams but filenames, a central system abstraction, cannot be part of a text stream without the potential for ambiguity/corruption (Is this newline actually the beginning of a new line or part of a foolish filenaming scheme?). Due to this we often have to choose between a simple, 80% solution (which is often sufficient) or a comparatively cumbersome approach.

The design decision was made long ago; it's not going anywhere; and in practice it isn't usually a problem. Still, I think would have been a good decision to have disallowed \t and \n in filenames. <insert visions of {file,path}names shuttling through pipes without a care in the world>

Regards,
Alister
 

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LEARN ABOUT XFREE86

zdiff

ZDIFF(1)						      General Commands Manual							  ZDIFF(1)

NAME

       zcmp, zdiff - compare compressed files

SYNOPSIS

       zcmp [ cmp_options ] file1 [ file2 ]
       zdiff [ diff_options ] file1 [ file2 ]

DESCRIPTION

       Zcmp  and  zdiff are used to invoke the cmp or the diff program on files compressed via gzip.  All options specified are passed directly to
       cmp or diff.  If only file1 is specified, it is compared to the uncompressed contents of file1.gz.  If two files are specified, their  con-
       tents  (uncompressed  if  necessary)  are  fed to cmp or diff.  The input files are not modified.  The exit status from cmp or diff is pre-
       served.

SEE ALSO

       cmp(1), diff(1), zmore(1), zgrep(1), znew(1), zforce(1), gzip(1), gzexe(1)

BUGS

       Messages from the cmp or diff programs may refer to file names such as "-" instead of to the file names specified.

																	  ZDIFF(1)
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