tar not reading if output directed to /dev/null Post: 302351501

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Operating Systems Linux Ubuntu tar not reading if output directed to /dev/null Post 302351501 by bakunin on Tuesday 8th of September 2009 06:57:21 PM

09-08-2009

Registered User

First off, I'd like to state that i do NOT have a problem. I just want to achieve a better understanding. So you don't need to tell me workarounds, as i have already found one.

Quote:

Originally Posted by thegeek

Before that why you would want to tar and check the integrity, better you can do by reading all the files !!

This is exactly what i was expecting tar to do: read all the files.

Quote:

Originally Posted by methyl

The parameter after "-f" is the archive filename. A value of "-" when there is no pipeline has no sensible meaning

Sorry, but this is simply not true: the dash as a filename is signifying <stdout> and if i use a redirection or a pipeline to manipulate tars output further should make no difference.

In fact (as i have stated in my first post) the command worked the way i wrote it when i used a real file (instead of /dev/null) as output destination. It is this inconsistency - the command reading all the files when a real file is the destination and not working, when the destination is /dev/null - i want to understand.

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LEARN ABOUT SUNOS

tar

tar.h(3HEAD)							      Headers							      tar.h(3HEAD)

NAME

       tar.h, tar - extended tar definitions

SYNOPSIS

       #include <tar.h>

DESCRIPTION

       The <tar.h> header defines header block definitions as follows.

       Name		  Description	     Value
       TMAGIC		  "ustar"	     ustar plus null byte
       TMAGLEN		  6		     length of the above
       TVERSION 	  "00"		     00 without a null byte
       TVERSLEN 	  2		     length of the above

       Typeflag field definitions:

       Name		  Description	     Value
       REGTYPE		  '0'		     regular file
       AREGTYPE 	  ''		     regular file
       LNKTYPE		  '1'		     link
       SYMTYPE		  '2'		     symbolic link
       CHRTYPE		  '3'		     character special
       BLKTYPE		  '4'		     block special
       DIRTYPE		  '5'		     directory
       FIFOTYPE 	  '6'		     FIFO special
       CONTTYPE 	  '7'		     reserved

       Mode field bit definitions (octal):

       Name		  Description	     Value
       TSUID		  04000 	     set UID on execution
       TSGID		  02000 	     set GID on execution
       TSVTX		  01000 	     on 	directories,
					     restricted     deletion
					     flag
       TUREAD		  00400 	     read by owner
       TUWRITE		  00200 	     write by owner special
       TUEXEC		  00100 	     execute/search by owner
       TGREAD		  00040 	     read by group
       TGWRITE		  00020 	     write by group
       TGEXEC		  00010 	     execute/search by group
       TOREAD		  00004 	     read by other
       TOWRITE		  00002 	     write by other
       TOEXEC		  00001 	     execute/search by other

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       pax(1), attributes(5), standards(5)

SunOS 5.10							    10 Sep 2004 						      tar.h(3HEAD)

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