Command Line Output Error Ubuntu
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Redirect Stdout And Stderr To Dev Null
answers are voted up and rise to the top How to redirect stderr to a file up vote 6 down vote favorite 1 While using nohup to put a command to run in background some of content appear in terminal. cp: error reading ‘/mnt/tt/file.txt’: Input/output error cp: failed to extend ‘/mnt/tt/file.txt’: Input/output error I want to save that content to a file. command-line redirect share|improve this question redirect stderr to file edited May 18 '15 at 13:42 asked May 18 '15 at 12:31 André M. Faria 3811618 add a comment| 1 Answer 1 active oldest votes up vote 11 down vote accepted There are two main output streams in Linux (and other OSs), standard output (stdout)and standard error (stderr). Error messages, like the ones you show, are printed to standard error. The classic redirection operator (command > file) only redirects standard output, so standard error is still shown on the terminal. To redirect stderr as well, you have a few choices: Redirect stderr to another file: command > out 2>error Redirect stderr to stdout (&1), and then redirect stdout to a file: command >out 2>&1 Redirect both to a file: command &> out For more information on the various control and redirection operators, see here. share|improve this answer answered May 18 '15 at 12:50 terdon♦ 41.6k685150 So 'hashdeep -rXvvl -j 30 -k checksums.txt /mnt/app/ >> result_hashdeep.txt 2> error_hashdeep.txt &' or 'hashdeep -rXvvl -j 30 -k checksums.txt /mnt/app/ >> result_hashdeep.txt 2>&1' or 'hashdeep -rXvvl -j 30 -k checksums.txt /mnt/app/ &> result_mixed.txt' –André M. Faria May 18 '15 at 12:59 1 @AndréM.Faria yes. But the last two commands
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 answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack append stderr and stdout to file Overflow the company Business Learn more about hiring developers or posting ads with us redirect stderr to dev null Ask Ubuntu Questions Tags Users Badges Unanswered Ask Question _ Ask Ubuntu is a question and answer site for Ubuntu users and redirect stderr tcsh developers. 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 top How to both display http://askubuntu.com/questions/625224/how-to-redirect-stderr-to-a-file a command line's output on console and save the output into a text file? up vote 22 down vote favorite 6 How can I run sudo apt-get install by BOTH seeing the process of installation (long in my case) and saving its output into a text file ? command-line apt share|improve this question edited Jun 20 '14 at 15:46 asked Jun 19 '14 at 13:06 user284234 Is only about apt-get right? http://askubuntu.com/questions/485495/how-to-both-display-a-command-lines-output-on-console-and-save-the-output-into –Braiam Jun 20 '14 at 20:52 @Braiam I think the solution I accepted can be applied to all other commands, do you think so ? –user284234 Jun 21 '14 at 8:32 add a comment| 5 Answers 5 active oldest votes up vote 17 down vote accepted use the script command. It will copy everything that goes to screen in a file script -c "sudo apt-get install things" script-file.script share|improve this answer answered Jun 19 '14 at 13:13 exore 37123 script sends the command output to a file, but does not show it on the screen. –Aaron Jun 19 '14 at 13:18 2 @BryceAtNetwork23. Did you try the command ? script does send output to screen. –exore Jun 19 '14 at 13:26 1 I did. I ran script -c "history" ~/hist.txt and saw output indicating Script started and Script done, but I didn't see output from the actual command on the screen. –Aaron Jun 19 '14 at 13:30 10 @BryceAtNetwork23 history is a shell builtint, not an external command. What happens is : 1) script starts, 2) script searches the history command, does not find it, so it guesses it should run this via a shell. 3) script runs the command history via a shell 4) a new shell starts a
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 answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn http://askubuntu.com/questions/350208/what-does-2-dev-null-mean more about hiring developers or posting ads with us Ask Ubuntu Questions Tags Users Badges Unanswered Ask Question _ Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute: http://www.cyberciti.biz/faq/how-to-redirect-output-and-errors-to-devnull/ 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 top What does 2>/dev/null mean…? up vote 52 down vote favorite 33 I want output error 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 Feb 26 '15 at 9:44 asked Sep 26 '13 at 8:21 Naive 67831322 add a comment| 4 Answers 4 active oldest votes up vote 83 down vote accepted The > operator redirects the output usually to a file but it can be to a device. You can also use >> to append. If you don't specify output error ubuntu a number then the standard output stream is assumed but you can also redirect errors > file redirects stdout to file 1> file redirects stdout to file 2> file redirects stderr to file &> file redirects stdout and stderr to file /dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output. share|improve this answer edited Sep 26 '13 at 13:55 answered Sep 26 '13 at 8:38 Warren Hill 10.2k104463 add a comment| up vote 10 down vote In short, it redirects stderr (fd 2) to the black hole (discard output of the command). Some more common use case command > /dev/null 2>&1 & run command in background, discard stdout and stderr command >> /path/to/log 2>&1 & run command and redirect stdout and stderr to log file share|improve this answer edited Dec 29 '14 at 12:51 Griwes 2191213 answered Sep 26 '13 at 8:32 Terry Wang 4,36921520 1 Is there a good reason to use > /dev/null 2>&1 instead of &> /dev/null? –Craig McQueen Nov 30 '15 at 6:43 3 @CraigMcQueen &> is new in Bash 4, the former is just the traditional way, I am just so used to it (easy to remember). –Terry Wang Nov 30 '15 at 12:24 add a comment| up vote 1 down vote dev/null treated as black hole in Linux/Unix, so you
BASH Shell, CentOS, Debian / Ubuntu, Fedora Linux, FreeBSD, HP-UX Unix, Linux, Openbsd, Programming, Solaris-Unix, Suse, Troubleshooting, Ubuntu Linux, UNIXHow do I redirect output and errors to /dev/null under bash / sh shell scripting? How do I redirect the output of stderr to stdout, and then redirect this combined output to /dev/null device? In Unix, how do I redirect error messages to /dev/null? You can send output to /dev/null, by using command >/dev/null syntax. However, this will not work when command will use the standard error (FD # 2). So you need to modify >/dev/null as follows to redirect both output and errors to /dev/null.
Syntax to redirect error and output messages to /dev/nullThe syntax discussed below works with Bourne-like shells, such as sh, ksh, and bash:$ command > /dev/null 2>&1 $ ./script.sh > /dev/null 2>&1 $ ./example.pl > /dev/null 2>&1ORcommand &>/dev/null job arg1 arg2 &>/dev/null /path/to/script arg1 &>/dev/nullYou can also use the same syntax for all your cronjobs to avoid emails and output / error messages: @hourly /scripts/backup/nas.backup >/dev/null 2>&1 OR @hourly /scripts/backup/nas.backup &>/dev/nullRedirect both standard error and standard out messages to a log fileYou can always redirect both standard error (stdin) and standard out (stdout) text to an output file or a log file by typing the following command:command > file 2>&1 /path/to/my/cool/appname > myapp.log 2>&1Want to close stdout and stderr for the command being executed on a Linux/Unix/BSD/OSX bash shell?Try the following syntax:## Thanks http://www.cyberciti.biz/faq/how-to-redirect-output-and-errors-to-devnull/#comment-40252 ## command 1>&- 2>&- ## Note: additional '&' at the end of job to put it in backgrounds ## job 1>&- 2>&- & command 1>&- 2>&- &See man pages: bash(1), ksh(1) Share this tutorial on:TwitterFacebookGoogle+Download PDF version Found an error/typo on this page?About the author: Vivek Gite is a seasoned sysadmin and a trainer for the Linux/Unix & shell scripting. Follow him on Twitter. OR read m