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How To Redirect Standard Error To A File In Unix

am a new Ubuntu Linux and bash shell user. I also know how to redirect output from display/screen to a file using the following syntax:

cmd > file ls > fileHowever, some time errors are displayed on screen. How do I store redirect stderr to dev null and redirect output from the computer screen to a file on a Linux or Unix-like systems?

Bash Redirect Stderr To Dev Null

Bash / ksh and other modern shell on Linux has three file descriptors:stdin (0)stdout (1)stderr (2)Syntax To redirect all output to fileThe syntax ambiguous output redirect is as follows to redirect output (stdout) as follows:command-name > output.txt command-name > stdout.txtSyntax To redirect all error to fileThe syntax is as follows to redirect errors (stderr) as follows:command-name 2> errors.txt command-name 2> stderr.txtSyntax to redirect both csh redirect stderr output (stdout) and errors (stderr) to different filesThe syntax:command1 > out.txt 2> err.txt command2 -f -z -y > out.txt 2> err.txtSyntax to redirect both output (stdout) and errors (stderr) to same fileThe syntax is:command1 > everything.txt 2>&1 command1 -arg > everything.txt 2>&1Syntax to redirect errors (stderr) to null or zero devicesData written to a null or zero special file is discarded by your system. This is useful to silence out errors (also know as ‘error spam'):command1

Redirect Stderr To Stdout Windows

2> /dev/null command1 2> /dev/zero command2 -arg 2> /dev/null command2 -arg 2> /dev/zeroTip: Use tee command to redirect to both a file and the screen same timeThe syntax is:command1 |& tee log.txt ## or ## command1 -arg |& tee log.txt ## or ## command1 2>&1 | tee log.txtAnother usage:#!/bin/bash # My script to do blah ... foo(){ : } 2>&1 | tee foo.logOR#!/bin/bash # My script to do blah ... { command1 command2 } 2>&1 | tee script.log 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 more like this:BASH Shell Redirect Output and Errors To /dev/nullBASH Shell: How To Redirect stderr To stdout ( redirect stderr to a File )Unix and Linux: Redirect Error Output To null CommandHow do I save or redirect stdout and stderr into different files?Linux / Unix Find Command: Avoid Permission Denied MessagesShell Script While Loop ExamplesPrinting output of c program to a file in LinuxUnix / Linux: Save Output To FileLinux iptables: Port Redirection ExampleApplescript: Run or Call a Shell Script{ 10 comments… add one } Andrey Oliveira June 23, 2014, 12:15 pmIn newer versions of bash and sh, for "Syntax to redirect both output (stdout) and errors (stderr) to same file" you can also use:com

>20.3. Applications

There are always three default files [1] open, stdin (the keyboard), stdout (the bash write to stderr screen), and stderr (error messages output to the screen). These, tee stderr and any other open files, can be redirected. Redirection simply means capturing output from a file, command,

Bash Redirect Stderr And Stdout To Different Files

program, script, or even code block within a script (see Example 3-1 and Example 3-2) and sending it as input to another file, command, program, or http://www.cyberciti.biz/faq/linux-redirect-error-output-to-file/ script.

Each open file gets assigned a file descriptor. [2] The file descriptors for stdin, stdout, and stderr are 0, 1, and 2, respectively. For opening additional files, there remain descriptors 3 to 9. It is sometimes useful to assign one of these additional file descriptors to stdin, stdouthttp://www.tldp.org/LDP/abs/html/io-redirection.html >, or stderr as a temporary duplicate link. [3] This simplifies restoration to normal after complex redirection and reshuffling (see Example 20-1).

COMMAND_OUTPUT > # Redirect stdout to a file. # Creates the file if not present, otherwise overwrites it. ls -lR > dir-tree.list # Creates a file containing a listing of the directory tree. : > filename # The > truncates file "filename" to zero length. # If file not present, creates zero-length file (same effect as 'touch'). # The : serves as a dummy placeholder, producing no output. > filename # The > truncates file "filename" to zero length. # If file not present, creates zero-length file (same effect as 'touch'). # (Same result as ": >", above, but this does not work with some shells.) COMMAND_OUTPUT >> # Redirect stdout to a file. # Creates the file if not present, otherwise appends to it. # Single-line redirection commands (affect only the line they are on): # -----------------------

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 http://stackoverflow.com/questions/7526971/how-to-redirect-both-stdout-and-stderr-to-a-file Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is http://unix.stackexchange.com/questions/79996/how-to-redirect-stdout-and-stderr-to-a-file-and-display-stderr-to-console a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up How to redirect both stdout and stderr to a file up vote 162 down redirect stderr vote favorite 45 Hi I am running a bash script that creates a log file for the execution of the command I use the following Command1 >> log_file Command2 >> log_file This only sends the standard output and not the standard error which appears on the terminal. Can I log both the stderr and stdout logged to a file? bash stdout stderr share|improve this question edited Sep 23 '11 at redirect stderr to 10:11 asked Sep 23 '11 at 9:35 sdmythos_gr 1,64621321 2 possible duplicate of Redirect stderr and stdout in a bash script –Nathan Aug 19 '14 at 19:35 Possible duplicate of How can I redirect and append both stdout and stderr to a file with Bash? –That1Guy May 5 at 15:19 add a comment| 5 Answers 5 active oldest votes up vote 235 down vote accepted If you want to log to the same file: command1 >> log_file 2>&1 If you want different files: command1 >> log_file 2>> err_file share|improve this answer answered Sep 23 '11 at 9:37 Mat 135k21235274 73 And just to save someone else the frustration, note that the order is important: 2>&1 needs to occur after >> log_file. –Rufflewind Jan 2 '14 at 6:34 2 Why >> and not > ? –user3527975 Mar 16 at 21:38 3 >> appends to the file, > overwrites. Search for "shell redirection" for more details. –Mat Mar 17 at 5:04 add a comment| up vote 119 down vote The simplest syntax to redirect both is: command &> logfile If you want to append to the file instead of overwrite: command &>> logfile share|improve this answer answered Sep 23 '11 at 10:14 Costi Ciudatu 20.5k4336

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 more about hiring developers or posting ads with us Unix & Linux Questions Tags Users Badges Unanswered Ask Question _ Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. 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 redirect stdout and stderr to a file and display stderr to console? up vote 14 down vote favorite 3 I know how to redirect to a file, and use tee; on a basic level. So $ alias outanderr='bash -c "echo stdout >&1; echo stderr >&2"' # A fake "application" displaying both output and error messages. $ outanderr 1>file # redirect stdout to a file, display stderr stderr $ outanderr 2>file # redirect stderr to a file, display stdout stdout $ outanderr 1>file 2>&1 # redirect both to a file, display nothing $ outanderr | tee file; echo "-- file contents --" && cat file # redirect stdout to a file, display both (note: order is messed up) stderr stdout -- file contents -- stdout $ outanderr 2>&1 | tee file; echo "-- file contents --" && cat file # redirect both to a file, display both stdout stderr -- file contents -- stdout stderr The question is: what to write in place of the questionmarks to get the output below: $ outanderr ???; echo "-- file contents --" && cat file # redirect both to a file, display stderr stderr -- file contents -- stdout stderr Constaints: Assuming bash. The order should be kept in the file. stderr contents are displayed in real time line by line, i.e. no buffering. Separate script files can be used. Magic may be necessary. bash files io-redirection share|improve this question edited May 1 '14 at 21:12 asked Jun 19 '13 at 14:39 TWiStErRob 173117 How much control of the outanderr program do you have? –Kevin Jun 19 '13 at 15:02 1 @Kevin I think the question is more generic than that. Here, outanderr is just an alias that prints a line to stdout and another to stderr. The idea (if it's possible) is to build a generic solution that could work with any program, without modifying them. –lgeorget Jun 19 '13 at 15:06 @lgeorget I understand that, but I don't believe it is possible to strictly meet all constraints in a

 

how to redirect standard error in csh

How To Redirect Standard Error In Csh p 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 more about hiring developers or posting ads p Csh Redirect Stderr To Dev Null p with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the csh redirect stderr to file Stack Overflow Community Stack Overflow is a community of million programmers just like you helping each other Join

how to redirect standard error

How To Redirect Standard Error p in BASH Shell Linux UNIXQ How do I redirect stderr to stdout How do I redirect stderr to a file A Bash and other modern shell provides I O redirection facility There are default standard files standard redirect stderr to dev null streams open a stdin - Use to get input keyboard i e data going into a p Redirect Stderr And Stdout To Dev Null p program center p b stdout - Use to write information screen c stderr - Use to write error message screen Understanding I O streams numbersThe Unix Linux

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How To Redirect Error In Csh p 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 more about hiring csh redirect stderr to dev null developers or posting ads with us Unix Linux Questions Tags Users Badges Unanswered Ask Question csh ambiguous output redirect Unix Linux Stack Exchange is a question and answer site for users of Linux FreeBSD and other Un x-like operating systems Join them csh it only takes

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Java Cmd Error Stream p here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta windows redirect stderr to stdout Discuss the workings and policies of this site About Us Learn dos redirect stderr to stdout more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us windows command line redirect output to file and screen Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of million programmers just like windows stderr