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Bash Error Output Redirection


For instance, if you open a file descriptor with exec 3>file, all the commands afterwards will inherit it. cmd 2>& 1 <<< stuff # Hideously Bad. When in doubt, I use 2>/dev/null. Notice that I am using stdout for something. Check This Out

The word after the <<< is expanded (variables, command substitutions, ...), but not pathname-expanded (*.txt, foo??.exe, ...), so: # this gives the contents of PATH variable cat <<< "$PATH" # this It's free: ©2000-2016 nixCraft. A little note for seeing this things: with the less command you can view both stdout (which will remain on the buffer) and the stderr that will be printed on the For example, this will still output an error message:ps -ef | grep | grep ps > /dev/null 2>&1 Reply Link nixCraft February 2, 2015, 8:14 pmTry:(ps -ef | grep | grep

Bash Redirect Error Output To File

A slightly more correct is: The output of the ‘command' is redirected to a ‘file-name' and the error chanel (that is the ‘2' is redirected to a pointer (?) of the 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 Wiki syntax is allowed: Please fill all the letters into the box to prove you're human.

The result of running a script having the above line and additionally this one: echo "Will end up in STDOUT(terminal) and /var/log/messages" ...is as follows: $ ./my_script Will end up in bad_command3 # Error message echoed to stderr, #+ and does not appear in $ERRORFILE. # These redirection commands also automatically "reset" after each line. #=======================================================================

now works as expected on OS X 10.11.1 (seems to be bash 3.2), just for Bash Redirect Stderr And Stdout To Same File So the input of the while loop never "sees" the "enter choice:" prompt, since there is no newline.

Sadly, I end up with a solution similar to Mr. Bash Redirect Error Output To /dev/null As an exercise, you can start with 1 pointing to file.stdout and 2 pointing to file.stderr, you will see why these redirections are very nice. Leffler, but I'll add that you can call useless from inside a Bash function for improved readability: #!/bin/bash function useless { /tmp/useless.sh | sed 's/Output/Useless/' } ERROR=$(useless) echo $ERROR All other Can anybody explain what exactly happens?

Reply Link Hugues November 12, 2013, 4:33 pml often do the following and I do not want an error (just a 0 length file) You get a valid output if the Bash Redirect Stderr And Stdout To Different Files Note: The order matters as liw.fi pointed out, 2>&1 1>file.log doesn't work. good explanation, I'd like to make a function on C that redirects STDIN and SDTOUT to an script, how can I do that, I mean, the exist a library's on C exec In Bash the exec built-in replaces the shell with the specified program.

  • Any suggestions?
  • So following two are the same command:command 2>&1 1>/dev/nullANDcommand 1>/dev/null 2>&1 Reply Link Anonymous August 25, 2012, 7:33 pmHello,The order is important :$ ls non_existing_folder 1>/dev/null 2>&1(no output)$ ls non_existing_folder 2>&1
  • Let's continue with the right part of the second pipe: | cmd3 3>&- 4>&- --- +-------------+ ( 0 ) ---->| 2nd pipe | --- +-------------+ --- +-------------+ ( 1 ) ---->|
  • It almost work, but not from xinted ;( share|improve this answer answered Apr 23 '09 at 13:14 log-control I'm guessing it doesn't work because of "/dev/fd/3 Permission denied".
  • These are the file descriptors of the inner {}.
  • Problem is users get confused by the "permission denied" msgs output by the "rm".
  • How to increase the population growth of the human race When taking passengers, what should I do to prepare them?

Bash Redirect Error Output To /dev/null

It seems that here-documents (tested on versions 1.14.7, 2.05b and 3.1.17) are correctly terminated when there is an EOF before the end-of-here-document tag. share|improve this answer answered Apr 23 '13 at 5:07 einstein6 192 add a comment| up vote 1 down vote "Easiest" way (bash4 only): ls * 2>&- 1>&-. Bash Redirect Error Output To File ERROR=$( { ./useless.sh | sed s/Output/Useless/ > outfile; } 2>&1 ) Note that the semi-colon is needed (in classic shells - Bourne, Korn - for sure; probably in Bash too). Bash Redirect Standard Error At the same time it copies the same input to FD #3(terminal) the second part, very similar, is about doing the same trick for STDERR and FDs #2 and #4.

It's equivalent to > TARGET 2>&1 Since Bash4, there's &>>TARGET, which is equivalent to >> TARGET 2>&1. his comment is here The "here document" will do what it's supposed to do, and the * will, too. TAG <<-TAG ... 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 Redirect Stderr

jack, 2012/03/02 17:41 Many thanks for these explanations! thanks Tony Jan Schampera, 2012/02/10 06:46 You pump STDERR of the command to descriptor 1, so that it can be transported by the pipe and seen as input by the tee Owens 47.3k9101190 2 This is the reason I included the pipe in my example. http://gatoisland.com/bash-redirect/bash-error-file-redirection.php echo -n . >&3 # Write a decimal point there.

If it's just to the console you redirect stdout to console and stderr to stdout to capture it: ERROR=$(./useless.sh | sed 's/Output/Useless/' 2>&1 1>/dev/ttyX) –Tim Kersten Mar 23 '11 at 11:41 Bash Redirect Stderr To Variable If the option noclobber is set with the set builtin, with cause the redirection to fail, when TARGET names a regular file that already exists. When sed starts to read the file, it contains nothing.

Multiple redirections More redirection operations can occur in a line of course.

The command will then start with: --- +-----------------------+ standard input ( 0 ) ---->| /dev/pts/5 | --- +-----------------------+ --- +-----------------------+ standard output ( 1 ) ---->| /dev/pts/5 | --- +-----------------------+ --- The other is to append. And avoid redirection in the command itself. Bash Redirect Stderr Pipe What is the sh -c command?

Why sed 's/foo/bar/' file >file Doesn't Work This is a common error, we want to modify a file using something that reads from a file and writes the result to stdout. They are set up from left to right. 2>&1 >file A common error, is to do command 2>&1 > file to redirect both stderr and stdout to file. Adopt A Jet/Book Is my workplace warning for texting my boss's private phone at night justified? navigate here EOF As you see, substitutions are possible.

no outgoing connection via ipv4 Using Map to convert Feet + Inches to Inches in a List of Lists So sayeth the Shepherd Skipping directly to level 4 Why don't most This is suitable sometimes for cron entries, if you want a command to pass in absolute silence.

 rm -f $(find / -name core) &> /dev/null 
This (thinking on the asked 5 years ago viewed 98630 times active 1 year ago Get the weekly newsletter! Is this true?

We start as in the previous example, and Bash sees > file: --- +-----------------------+ standard input ( 0 ) ---->| /dev/pts/5 | --- +-----------------------+ --- +-----------------------+ standard output ( 1 ) op is <, >, >>, >|, or <>: < if the file decriptor in lhs will be read, > if it will be written, >> if data is to be appended You da man! –Ogre Psalm33 Aug 4 '10 at 12:54 7 On AIX (ksh) your solution works. That is, to design a wrapper program that will assign the called program to redirect its 0-2 to named pipes.

Reply Link ma thesh February 2, 2015, 6:16 pmHow to get the error help in shell window Reply Link Alex October 19, 2015, 10:02 amThanks! Is 8:00 AM an unreasonable time to meet with my graduate students and post-doc? Realism of a setting with several sapient anthropomorphic animal species Are there any 'smart' ejection seats? Closing The File Descriptors Closing a file through a file descriptor is easy, just make it a duplicate of -.

Any idea why? –Alexandre Holden Daly May 30 '14 at 12:12 1 Note that (by default) this has the side-effect that $? The output from stdout and stderr should go to a file, to see the scripts progress at the terminal I wanted to redirect the output of some echo commands to the

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