Home > Bash Redirect > Bash Error Output Redirect

Bash Error Output Redirect


bash share|improve this question edited Aug 19 '14 at 22:36 Steven Penny 1 asked Jun 7 '10 at 14:36 BCS 25.4k41145245 add a comment| 13 Answers 13 active oldest votes up a filename that contains a space). Let's see another use case. What are the canonical white spaces? http://sovidi.com/bash-redirect/bash-redirect-error-output.php

These, and any other open files, can be redirected. Try this: declare tT="A\nB\nC\n" # Should have three lines here echo -e "tT($tT)" # Three lines, confirmed echo -e "sort($(sort <<< $tT))" # Sort outputs three lines echo -e "$tT" | A simple visual puzzle to die for What does the "Phi" sign stand for in musical notation? A function, on the other hand, is placed into the currently running shell's environment.

Bash Redirect Error Output To File

ls -yz 2>&1 >> command.log # Outputs an error message, but does not write to file. # More precisely, the command output (in this case, null) #+ writes to the file, bad_command2 2>>$ERRORFILE # Error message appended to $ERRORFILE. If you don't specify a program, the redirection after exec modifies the file descriptors of the current shell. Applications

There are always three default files [1] open, stdin (the keyboard), stdout (the screen), and stderr (error messages output

EOF These are 2 things: a redirection (here-document EOF) a pathname expansion which MAY generate commandline arguments to cat These things are independent. One of the ways to get the effect you want, you would run your script and direct stderr to somewhere else at the same time, so, ./myscript 2>> errors.txt at that My modified script: filename="/home/ronnie/tmp/hello" date= $(date) echo "$date" >> $filename 2>> $filename #Also tried echo "$date" >> $filename 2>&1 I was thinking that above script will redirect the error test.sh: line Bash Redirect Stderr And Stdout To Same File Using builtins, writing functions are quite cheap, because there is no need to create (execute) a process (-environment).

As with >, < can be used to open a new file descriptor for reading, command 3&2; Religious supervisor wants to thank god in the acknowledgements How does Gandalf get informed of Bilbo's 111st birthday party? Jan Schampera, 2010/04/28 22:02 Try this.

How to make different social classes look quite different? Bash Redirect Stderr And Stdout To Different Files Religious supervisor wants to thank god in the acknowledgements Meaning of Guns and ghee When taking passengers, what should I do to prepare them? share|improve this answer edited Sep 11 at 15:16 answered Aug 29 at 1:50 osexp2003 63666 add a comment| Your Answer draft saved draft discarded Sign up or log in Sign The shell's error stream is not redirected at this point.

Bash Redirect Error Output To /dev/null

Next Previous Contents Advanced Bash-Scripting Guide: PrevNextChapter 20. as you can see. Bash Redirect Error Output To File If not, why? Bash Redirect Standard Error At that stage, you're not redirecting stderr anywhere.

Regards Armin P.S.: I have some problems with formatting, esp. http://sovidi.com/bash-redirect/bash-redirect-error-output-append.php monitor) stderr2standard error output stream (usually also on monitor) The terms "monitor" and "keyboard" refer to the same device, the terminal here. How to increase the population growth of the human race What could cause the throttle to stick in my Ford Ranger? Therefore you'll still see the error message. Bash Redirect Stderr To Dev Null

Use the long form >foo 2>&1. (see: obsolete) # Good! Any suggestions? Since shells fundamentally use whitespace to delimit fields in general, it is visually much clearer for each redirection to be separated by whitespace, but grouped in chunks that contain no unnecessary http://sovidi.com/bash-redirect/bash-redirect-error-to-output.php Redirecting output and error output &> TARGET >& TARGET This special syntax redirects both, stdout and stderr to the specified target.

bash stdout stderr share|improve this question asked Oct 19 '12 at 12:25 ronnie 233238 add a comment| 2 Answers 2 active oldest votes up vote 6 down vote accepted The line Bash Redirect Stderr To Variable The TARGET is truncated before writing starts. The position on the commandline does not really matter, a redirection (here document) is a redirection: # cat the two files plus "hello world" from standard input by here document redirection

bad_command3 # Error message echoed to stderr, #+ and does not appear in $ERRORFILE. # These redirection commands also automatically "reset" after each line. #=======================================================================

cmd 2>& 1 <<< stuff # Hideously Bad. The quotation marks also make my editor syntax-highlight some message as being data rather than a command, which can be visually helpful in parsing a shell script. –Brandon Rhodes May 29 TAG <<-TAG ... Bash Redirect Stderr Pipe exec 1<>$LOG_FILE # Redirect STDERR to STDOUT exec 2>&1 echo "This line will appear in $LOG_FILE, not 'on screen'" Now, simple echo will write to $LOG_FILE.

You can redirect the file descriptors of the shell permanently (or at least until the next time you change them) by using a redirection on the exec builtin with no command ERRORFILE=script.errors bad_command1 2>$ERRORFILE # Error message sent to $ERRORFILE. share|improve this answer answered Jun 7 '10 at 14:37 Matthew Flaschen 174k28368450 7 It shouldn't cause errors, but I might be more likely to. his comment is here stdout goes to /dev/null, stderr still (or better: "again") goes to the terminal.

That something written on the file descriptor 2 will go where file descriptor 1 goes. In it, you'll get: The week's top questions and answers Important community announcements Questions that need answers see an example newsletter By subscribing, you agree to the privacy policy and terms Now for the left part of the second pipe {…} 2>&1 >&4 4>&- | --- +-------------+ --- +-------------+ ( 0 ) ---->| /dev/pts/5 | ( 3 ) ---->| /dev/pts/5 | --- For instance, let's close stdin <&- and stderr 2>&-: bash -c '{ lsof -a -p $$ -d0,1,2 ;} <&- 2>&-' COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME bash 10668

Often nothing. Syntax I used to have trouble choosing between 0&<3 3&>1 3>&1 ->2 -<&0 &-<0 0<&- etc… (I think probably because the syntax is more representative of the result, i.e., the redirection, Let us see how to duplicate them, starting with the classic 2>&1. Redirecting output N > TARGET This redirects the file descriptor number N to the target TARGET.

How do I redirect stderr to a file? Thank you! 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. I know I can do echo foo 1>&2 but it's kinda ugly and, I suspect, error prone (e.g.

It is sometimes useful to assign one of these additional file descriptors to stdin, stdout, or stderr as a temporary duplicate link. [3] This simplifies restoration E.g. share|improve this answer answered Oct 19 '12 at 12:30 EightBitTony 11.3k3247 Thanks for the explanation. –ronnie Oct 19 '12 at 12:33 1 Another strategy would be to surround There are other problems as well.

Why? Cool. You can even combine sudo to downgrade to a log user account and add date's subject and store it in a default log directory :) Reply Link Alejandro April 22, 2015, M>N # "M" is a file descriptor, which defaults to 1, if not explicitly set. # "N" is a filename. # File descriptor "M" is redirect to file "N." M>&N #

read -n 4 <&3 # Read only 4 characters.