Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: tar not reading if output directed to /dev/null
Operating Systems Linux Ubuntu tar not reading if output directed to /dev/null Post 302351370 by bakunin on Tuesday 8th of September 2009 10:20:28 AM
Old 09-08-2009
tar not reading if output directed to /dev/null
I stumbled across a somewhat strange behavior of tar and find no explanation for it: i was testing a DVD for read errors and thought to simply tar the content and direct the output to /dev/null:

Code:
tar -cvf - /my/mountpoint/*ts > /dev/null

This way i expected the system to read the complete content and eventually to report a read error if there is one. To my amazement the command came back immediately without any error. Still i didn't believe it had read anything (save for maybe the directory information) so i directed the output to a real file instead.
Code:
tar -cvf - /my/mountpoint/*ts > /tmp/somefile

This time tar did read the files and subsequently reported the read error i was expecting in one file.

My question is, why didn't it read the files before? Is there something i am missing?

bakunin
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

/dev/null

Hi , I am importing some table from /dev/null i dont understand what is /dev/null Sorry i am new to UNIX sam71 (3 Replies)
Discussion started by: sam71
3 Replies

2. Solaris

URGENT - setup port and dump all output to /dev/null or a file

Please help urgently. I need to setup up some sort of service on a solaris server on a port. I dont need it do anything special, anything that is sent to this port from an external server should be dump to /dev/null or a flat file.. Can you help urgently? (1 Reply)
Discussion started by: frustrated1
1 Replies

3. Solaris

What is /dev/tty /dev/null and /dev/console

Hi, Anyone can help My solaris 8 system has the following /dev/null , /dev/tty and /dev/console All permission are lrwxrwxrwx Can this be change to a non-world write ?? any impact ?? (12 Replies)
Discussion started by: civic2005
12 Replies

4. Shell Programming and Scripting

/dev/null what is the use of it?

when do you use the path /dev/null (3 Replies)
Discussion started by: webmunkey23
3 Replies

5. UNIX for Dummies Questions & Answers

cp output /dev/null results in not a directory

Hello, I am working on a script to measure the read performance of a busybox environment. The logical choice is to use a command line like: (time cp * /dev/null) 2> /tmp/howlong.txt Ah, the rub is cp or /dev/null will only accept a single file at a time. The result in the txt file is and... (1 Reply)
Discussion started by: stevesmo
1 Replies

6. Shell Programming and Scripting

Error output of cat to /dev/null

Hello, I'm trying to send the error output of a 'cat' operation to /dev/null like this: cat /dirA/dirB/temp*.log > /dirA/dirB/final.log 2>/dev/null This works perfectly in a terminal, but not when placed in a script. If there are no files matching temp*.log the script outputs an error... (7 Replies)
Discussion started by: Nils88
7 Replies

7. UNIX for Dummies Questions & Answers

/dev/null 2>&1 Versus /dev/null 2>1

How are these two different? They both prevent output and error from being displayed. I don't see the use of the "&" echo "hello" > /dev/null 2>&1 echo "hello" > /dev/null 2>1 (3 Replies)
Discussion started by: glev2005
3 Replies

8. Shell Programming and Scripting

Redirecting standard out to /dev/null goes to file "/dev/null" instead

I apologize if this question has been answered else where or is too elementary. I ran across a KSH script (long unimportant story) that does this: if ; then CAS_SRC_LOG="/var/log/cas_src.log 2>&1" else CAS_SRC_LOG="/dev/null 2>&1" fithen does this: /usr/bin/echo "heartbeat:... (5 Replies)
Discussion started by: jbmorrisonjr
5 Replies

9. Shell Programming and Scripting

redirect the audio output to /dev/null

I'm using an text-to-speech synthesis in a script, and I need to redirect it's output to /dev/null how can I do that ? And how to redirect the stream to his normal output then （sound card ) ? thankx (2 Replies)
Discussion started by: firelink
2 Replies

10. Shell Programming and Scripting

2>/dev/null

Friends have the following problem a search may not find anything which would correct example: ls -ltr *prueba.txt | nawk '{ print $9 }' > Procesar.dat 2>/dev/null When he finds nothing gives me the following error ls: prueba.txt: No such file or directory because 2> / dev / null... (4 Replies)
Discussion started by: tricampeon81
4 Replies

LEARN ABOUT DEBIAN

dlb

DLB(6)								   Games Manual 							    DLB(6)

NAME

       dlb - NetHack data librarian

SYNOPSIS

       dlb { xct } [ vfIC ] arguments...  [ files...  ]

DESCRIPTION

       Dlb  is	a file archiving tool in the spirit (and tradition) of tar for NetHack version 3.1 and higher.	It is used to maintain the archive
       files from which NetHack reads special level files and other read-only information.  Note that like tar the command and	option	specifiers
       are specified as a continuous string and are followed by any arguments required in the same order as the option specifiers.

       This facility is optional and may be excluded during NetHack configuration.

COMMANDS

       The x command causes dlb to extract the contents of the archive into the current directory.

       The c command causes dlb to create a new archive from files in the current directory.

       The t command lists the files in the archive.

OPTIONS AND ARGUMENTS

       v	   verbose output

       f archive   specify the archive.  Default if f not specified is LIBFILE (usually the nhdat file in the playground).

       I  lfile     specify  the  file containing the list of files to put in to or extract from the archive if no files are listed on the command
       line.  Default for archive creation if no files are listed is LIBLISTFILE.

       C dir	   change directory.  Changes directory before trying to read any files (including the archive and the lfile).

EXAMPLES

       Create the default archive from the default file list:
		   dlb c

       List the contents of the archive 'foo':
		   dlb tf foo

AUTHOR

       Kenneth Lorber

SEE ALSO

       nethack(6), tar(1)

BUGS

       Not a good tar emulation; - does not mean stdin or stdout.  Should include an optional compression facility.  Not all read-only	files  for
       NetHack can be read out of an archive; examining the source is the only way to know which files can be.

4th Berkeley Distribution					    28 Oct 1993 							    DLB(6)
All times are GMT -4. The time now is 06:32 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy