Error Redirection In Shell Script
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12, 2008 in BASH Shell, Linux, UNIXQ. How do I redirect stderr to stdout? How do I redirect stderr to error and output redirection in unix a file? A. Bash and other modern shell provides I/O redirection facility.
Shell Script Redirect Error To Null
There are 3 default standard files (standard streams) open: [a] stdin - Use to get input (keyboard) shell script redirect stdout i.e. data going into a program.
[b] stdout - Use to write information (screen)[c] stderr - Use to write error message (screen)Understanding I/O streams numbersThe Unix / LinuxShell Script Redirect Stdin
standard I/O streams with numbers:HandleNameDescription0 stdin Standard input1 stdout Standard output2 stderr Standard errorRedirecting the standard error stream to a fileThe following will redirect program error message to a file called error.log: $ program-name 2> error.log
$ command1 2> error.logRedirecting the standard error (stderr) and stdout to fileUse the following syntax: $ command-name &>file OR shell script redirect stderr to stdout $ command > file-name 2>&1 Another useful example: # find /usr/home -name .profile 2>&1 | moreRedirect stderr to stdoutUse the command as follows: $ command-name 2>&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 more like this:How do I save or redirect stdout and stderr into different files?Linux Redirect Error Output To FileBASH Shell Redirect Output and Errors To /dev/nullUnix and Linux: Redirect Error Output To null CommandPrinting output of c program to a file in LinuxUnix / Linux: Save Output To FilePython Run External Command And Get Output On Screen or In VariablePython Execute Unix / Linux Command ExamplesLinux / Unix Find Command: Avoid Permission Denied MessagesHow to gzip and keep original file on Unix or Linux command line{ 11 comments… add one } Sayed Ahmad February 12, 2012, 12:11 amWhat this mean? $ command > file-name 2>&1 Reply Li
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Shell Script Redirect Stderr And Stdout To File
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Shell Script Redirect Stderr To Dev Null
Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign shell script redirect stderr to variable up Redirect stderr and stdout in a Bash script up vote 367 down vote favorite 118 I want to redirect both stdout and stderr of a process to a single file. How do I do that in Bash? bash shell redirect http://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/ pipe share|improve this question edited Nov 2 '15 at 12:01 Peter Mortensen 10.2k1369107 asked Mar 12 '09 at 9:14 flybywire 64.7k145335457 add a comment| 9 Answers 9 active oldest votes up vote 421 down vote accepted Take a look here. Should be: yourcommand &>filename (redirects both stdout and stderr to filename). share|improve this answer edited Oct 7 '10 at 5:44 David Johnstone 14k115568 answered Mar 12 '09 at 9:17 dirkgently 74.3k1293162 6 Somebody should restore to the second edit of this comment. Supplementary http://stackoverflow.com/questions/637827/redirect-stderr-and-stdout-in-a-bash-script 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 Bash Hackers Wiki. Is it? –Salman Abbas Jul 11 '12 at 1:10 7 According to wiki.bash-hackers.org/scripting/obsolete, it seems to be obsolete in the sense that it is not part of POSIX, but the bash man page makes no mention of it being removed from bash in the near future. The man page does specify a preference for '&>' over '>&', which is otherwise equivalent. –chepner Jul 16 '12 at 20:45 6 I guess we should not use &> as it is not in POSIX, and common shells such as "dash" do not support it. –Sam Watkins Apr 23 '13 at 8:24 11 An extra hint: If you use this in a script, make sure it starts with #!/bin/bash rather than #!/bin/sh, since in requires bash. –Tor Klingberg Oct 1 '13 at 17:47 | show 7 more comments up vote 261 down vote do_something 2>&1 | tee -a some_file This is going to redirect stderr to stdout and stdout to some_file and print it to stdout. share|improve this answer edited Oct 27 '15 at 10:33 rubenvb 41.7k13103190 answered Mar 12 '09 at 9:16 Marko 17.9k125999 3 I was searching SO for how to do this with pipe and tee. You da man! –Ogre Psalm33 Aug 4 '10 at 12:54 7 On AIX (ksh) your
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 http://unix.stackexchange.com/questions/70963/difference-between-2-2-dev-null-dev-null-and-dev-null-21 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 http://sc.tamu.edu/help/general/unix/redirection.html 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 shell script top Difference between 2>&-, 2>/dev/null, |&, &>/dev/null and >/dev/null 2>&1 up vote 74 down vote favorite 60 Just looking for the difference between 2>&- 2>/dev/null |& &>/dev/null >/dev/null 2>&1 and their portability with non-Bourne shells like tcsh, mksh, etc. shell io-redirection file-descriptors csh portability share|improve this question edited May 21 '14 at 8:40 Gilles 371k696751126 asked Apr 3 '13 at 1:25 Det 483156 1 Note that, while mksh supports &> for GNU bash compatibility, shell script redirect it’s strongly encouraged to not use this, as parsing it can break the semantics of existing POSIX scripts, and mksh disables that in POSIX mode already. –mirabilos Feb 27 '14 at 13:56 add a comment| 2 Answers 2 active oldest votes up vote 103 down vote accepted For background: a number 1 = standard out (i.e. STDOUT) a number 2 = standard error (i.e. STDERR) if a number isn't explicitly given, then number 1 is assumed by the shell (bash) First let's tackle the function of these. For reference see the Advanced Bash-Scripting Guide. Functions 2>&- The general form of this one is M>&-, where "M" is a file descriptor number. This will close output for whichever file descriptor is referenced, i.e. "M". 2>/dev/null The general form of this one is M>/dev/null, where "M" is a file descriptor number. This will redirect the file descriptor, "M", to /dev/null. 2>&1 The general form of this one is M>&N, where "M" & "N" are file descriptor numbers. It combines the output of file descriptors "M" and "N" into a single stream. |& This is just an abbreviation for 2>&1 |. It was added in Bash 4. &>/dev/null This is just an abbreviation for >/dev/null 2>&1. It redirects file descriptor 2 (STDERR) and descriptor 1 (STDOUT) to /dev/null. >/dev/null This is just an abbreviation for 1>/de
is connected to the terminal keyboard and standard output and error to the terminal screen. The way of indicating an end-of-file on the default standard input, a terminal, is usually