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Because I don't see how using tar to compress a directory into a tar file could possibly cause any type of errors. Not the answer you're looking for? Why is international first class much more expensive than international economy class? use: command 2>&1 1>/dev/null Reply Link nixCraft October 6, 2011, 12:54 am No, it does not matters.
Draw an hourglass Why is the bridge on smaller spacecraft at the front but not in bigger vessel? I'm Baron Schwartz, the founder and CEO of VividCortex. Now, if you execute the command uptime in the cornjob as follows: uptime >/dev/null 2>&1 2>&1 means a redirection of the chanel 2 (stderr) to the chanel 1 (stdout). Sometimes they’re not named, they’re numbered!
Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist? Disproving Euler proposition by brute force in C Would it be ok to eat rice using spoon in front of Westerners? But so there's no performance difference or some such with 2>&- vs 2>/dev/null (other than that some "poorly" written programs don't undrestand 2>&- correctly)? –Det Apr 6 '13 at 14:38 1 1 Dev Null Browse other questions tagged command-line io-redirection or ask your own question.
I've not dealt much with other shells outside of csh and tcsh. & Dev Null cd /home # This creates the archive tar cf /var/tmp/home_franky.tar franky > /dev/null 2>&1 # First remove the old bzip2 file. They were in zsh from the start and have only been added recently to bash. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the
As for why tar can cause errors: because the target directory does not exist, because the source doesn't, because you don't have write access to the target, or read to the /dev/null 2 &1 Ambiguous Output Redirect The program usually prints to standard output, and sometimes prints to standard error. Draw an hourglass Save a JPG without a background What's the point of Pauli's Exclusion Principle if time and space are continuous? Problems with amsmath Does the Iron Man movie ever establish a convincing motive for the main villain?
Didn't know that one. Something like: (your_command) 1>/dev/null should leave errors alone, that is, going to stout where you can see them. Redirect Error To Dev Null share|improve this answer edited Sep 27 '13 at 12:23 answered Sep 26 '13 at 8:31 sivann 28226 2 There is absolutely nothing wrong if you use 2>/dev/null. Redirect Only Stdout To Dev Null This site is not affiliated with Linus Torvalds or The Open Group in any way.
Both outputs are now on the same chanel (1). >/dev/null: means that the standard output (and the standard error output) is sent to /dev/null. /dev/null is a special file: Data written Check This Out rm /var/tmp/home_franky.tar.bz2 2> /dev/null bzip2 /var/tmp/home_franky.tar # Copy the file to another host - we have ssh keys for making this work without intervention. The built-in numberings for them are 0, 1, and 2, in that order. So why does that also go to /dev/null? Redirect Output To Null Windows
Since STDERR is now going to STDOUT (because of 2>&1) both STDERR and STDOUT ends up in the blackhole /dev/null. Related 17How to redirect output of a running program to /dev/null24Why is redirecting STDERR to /dev/null done this way?3find with multiple -exec options; redirecting &>/dev/null for one exec command sends process Reply Link Jonathan May 26, 2009, 9:31 pm Thanks! Source Limit Notation.
The chunk >/dev/null is redirecting stdout to /dev/null. '2>&1' is redirecting the error stream to the output stream, which has been redirected to /dev/null. Redirect Stderr To Dev Null And Stdout To File share|improve this answer answered Oct 21 '14 at 14:07 Ambrevar 13413 add a comment| up vote 1 down vote Redirection Bash's reference manual says: The operator [n]>&word is used [...] to It redirects file descriptor 1 (STDOUT) to /dev/null.
up vote 54 down vote favorite 34 I want one or two line description about the following command line: grep -i 'abc' content 2>/dev/null command-line grep stdout share|improve this question edited You can, however, do this: exec 2>/dev/null I wouldn't recommend doing this outside of a script. Does Anna know what a ball is? Redirect Stdin To /dev/null Given that context, you can see the command above is redirecting standard output into /dev/null, which is a place you can dump anything you don’t want (often called the bit-bucket), then
It's free: ©2000-2016 nixCraft. Reply Link Hugues November 12, 2013, 4:33 pm l often do the following and I do not want an error (just a 0 length file) You get a valid output if As such, no output is produced and no mail is sent. have a peek here How to explain centuries of cultural/intellectual stagnation?
cron will only email you if there is some output from you job. DDoS: Why not block originating IP addresses?