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Redirect Output Bash Error

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So the 4>&- makes sure that the inner compound command will not inherit file descriptor four, and the 3>&- will not inherit file descriptor three, so command1 gets a 'cleaner', more Follow him on Twitter. Here strings <<< WORD The here-strings are a variation of the here-documents. Any idea why? –Alexandre Holden Daly May 30 '14 at 12:12 1 Note that (by default) this has the side-effect that $? have a peek at this web-site

For instance: one of or any piped combination of 'tee', 'grep', 'sed', ... The other is to append. By using: VALUE=$(might_fail | piping; exit ${PIPESTATUS[0]}) I get want I wanted. –vaab Jun 23 '14 at 8:47 @vaab, that syntax looks really nice but I am confused on The reason is unknown, but it seems to be done on purpose. http://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/

Redirect Stderr To File

I think that this is because $() launches a sub process which no longer has access to the file descriptor in /dev/fd which is owned by the parent process. You could also move the inner 4>&- next to the 3>&-, but I figure why not just limit its scope as much as possible. Cool as fuck. stdout goes to /dev/null, stderr still (or better: "again") goes to the terminal.

Bonus: in the end the exit status is actually the exit status and not some string in a file. asked 6 years ago viewed 201371 times active 4 months ago Blog Stack Overflow Podcast #92 - The Guerilla Guide to Interviewing Linked 48 How can I redirect STDERR to STDOUT, What happens if the same field name is used in two separate inherited data templates? Ambiguous Output Redirect Avoid referencing file descriptors above 9, since you may collide with file descriptors Bash uses internally.

It does appear to be working on my machine which runs Gnu bash v3.2.48. –James Wald Apr 10 '14 at 7:32 5 @CostiCiudatu the &>> operator does not seem to Supplementary info to the question shouldn't be removed, especially in a 6 month old answer. –Jeff Ferland Sep 1 '09 at 14:14 13 This syntax is deprecated according to the In practice, it could be a pipe, socket or whatever. Bonuses Next Previous Contents Advanced Bash-Scripting Guide: PrevNext

Chapter 20.

more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation Tcsh Redirect Stderr more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Should I define the relations between tables in database or just in code? Another cool solution is about redirecting to both std-err/out AND to logger or log file at once which involves splitting "a stream" into two.

Bash Redirect Stdout And Stderr To Dev Null

Please keep this field empty: Show pagesource Old revisions Backlinks syntax/redirection.txt ยท Last modified: 2013/04/14 14:30 by thebonsai This site is supported by Performing Databases - your experts for database An alternative approach Ideally we would like the following: log messages sent to syslog stdout and stderr kept separate stdout and stderr message order preserved We’ve established that we can’t have Redirect Stderr To File How does a migratory species advance past the Stone Age? Redirect Stderr To Dev Null exec 3>&1 4>&2 1> >(tee >(logger -i -t 'my_script_tag') >&3) 2> >(tee >(logger -i -t 'my_script_tag') >&4) trap 'cleanup' INT QUIT TERM EXIT get_pids_of_ppid() { local ppid="$1" RETVAL='' local pids=`ps x

Testing it out Let’s write a very simple test script, logger_test: #!/bin/bash exec 1> >(logger -s -t $(basename $0)) 2>&1 echo "writing to stdout" echo "writing to stderr" >&2 When we Check This Out Browse other questions tagged bash stdout stderr or ask your own question. While command1 is running, its stdout is being piped to command2 (printf's output never makes it to command2 because we send it to file descriptor 3 instead of 1, which is Deconstructing the command The whole line again: exec 1> >(logger -s -t $(basename $0)) 2>&1 exec is a bash builtin, so to see what it does, we run help exec: exec: Bash Redirect Stderr To Dev Null

You da man! –Ogre Psalm33 Aug 4 '10 at 12:54 7 On AIX (ksh) your solution works. This would have saved me from looking it up, but then again I wouldn't have learned the other stuff I saw when I found that out! –Mark Edington Apr 26 at Reply Link TodorMinchev May 14, 2013, 9:03 pm RudyD +1 :) Reply Link Daniel August 26, 2013, 7:22 pm Actually it means "first redirect STDERR to STDOUT, so any errors printed Source If you have to use operands (e.g.

If the square root of two is irrational, why can it be created by dividing two numbers? Bash Echo To Stderr If you just need to redirect in/out of a command you call from your script, the answers are already given. Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist?

I don't think there's an easy way to do it.

Why did the distance requirement for my buddy change? Reply Link Shane Hathaway February 24, 2012, 1:02 am Sayed: that line means execute the command while redirecting both stdout and stderr to a file given by file-name. Reusable Matrix block types more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Redirect All Output To File Process substitution has bought me the ability to work with a data stream which is no longer in STDERR, unfortunately I don't seem to be able to manipulate it the way

The close isn't really needed if the script exits immediately afterwards. –Jonathan Leffler Jun 11 '09 at 22:01 How would I capture both stderr and stdout in variables? –Gingi Redirecting output N > TARGET This redirects the file descriptor number N to the target TARGET. Redirecting output and error output &> TARGET >& TARGET This special syntax redirects both, stdout and stderr to the specified target. have a peek here share|improve this answer edited Oct 7 '10 at 5:44 David Johnstone 14.1k115568 answered Mar 12 '09 at 9:17 dirkgently 74.6k1294163 6 Somebody should restore to the second edit of this

Does catching/throwing exceptions render an otherwise pure method to be impure? You have to swap the order to make it do what you want: { echo OUTPUT; echo ERRORS >&2; } 1>/dev/null 2>&1 Examples How to make a program quiet (assuming all How is being able to break into any linux machine through grub2 secure? When a pipe or "|" operator is present on the command line, the first thing to happen is that bash creates a fifo and points the left side command's FD 1

If you write a script that outputs error messages, please make sure you follow this convention! I'll simplify it and hope I interpreted it right: cat <

Appending redirected output and error output To append the cumulative redirection of stdout and stderr to a file you simply do >> FILE 2>&1 &>> FILE Transporting stdout and stderr through Nothing goes to the pipe, and thus "grep" will close out without displaying anything on the screen. So you stil get to see everything! After checking this, I know I won't make this mistake again. –Stephan Oct 11 '12 at 14:34 @Stephan cheers, this has also been discussed here. :) –Shadow Wizard Oct

If instead, you run the following: command >/dev/null 2>&1 | grep 'something' Here's what happens: a pipe is created and "command FD 1" and "grep FD 0" are pointed to it bash stdout stderr share|improve this question edited Sep 23 '11 at 10:11 asked Sep 23 '11 at 9:35 sdmythos_gr 1,67121321 2 possible duplicate of Redirect stderr and stdout in a stdout=$(echo good; echo bad >&2) 2>&1 | read stderr; echo "stdout=>$stdout"; echo "stderr=>$stderr" stdout=>good stderr=>bad –Bruce Mar 12 '14 at 3:06 | show 2 more comments up vote 28 down vote Bash 4 introduced a warning message when end-of-file is seen before the tag is reached.