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Bash Redirect Standard Output And Error


So you stil get to see everything! in the first example you wrote: exec 1<>$LOG_FILE . The redirection operators are checked whenever a simple command is about to be executed. The TARGET is not truncated before writing starts. this contact form

The tee command writes your original standard error output to the file plus outputs it to its STDOUT. TAG A here-document is an input redirection using source data specified directly at the command line (or in the script), no "external" source. To the author of the original post, It depends what you need to achieve. Why does Windows show "This device can perform faster" notification if I connect it clumsily?

Bash Redirect Standard Output To File

Changing STDOUT after STDERR had been redirected to STDOUT won't change STDERR. SyntaxDescription FILENAMEreferences a normal, ordinary filename from the filesystem (which can of course be a FIFO, too. How would family relationships change if legal system uses collective punishment?

  1. What does an 'ü' mean?
  2. use: command 2>&1 1>/dev/null Reply Link nixCraft October 6, 2011, 12:54 amNo, it does not matters.
  3. 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,
  4. And yes, during my research I found some weirdness in the Bash manual page about it, I will ask on the mailing list.
  5. Natural construction How to extrude a face parallel to another?
  6. John, 2015/10/28 21:59 Probably worth highlighting the link with Process Substitution in a more prominent way than the "See Also: process substitution syntax" link, since it's a close relative and possibly

It's equivalent to > TARGET 2>&1 Since Bash4, there's &>>TARGET, which is equivalent to >> TARGET 2>&1. Jan Schampera, 2010/04/28 22:02 Try this. Bash reads (stdin) from this terminal and prints via stdout and stderr to this terminal. --- +-----------------------+ standard input ( 0 ) ---->| /dev/pts/5 | --- +-----------------------+ --- +-----------------------+ standard output Bash Redirect Stderr To Stdout Tee First, a redirection into cat using a "here string".

To do this, we redirect stdout to the file we want to modify. Redirect Standard Output And Error To Dev Null It seems that /dev/stderr can have problem in cron. I don't know a global method (exec or thelike) off my head. This is clearly a simple commmand with two arguments and 4 redirections cmd arg1 arg2 /dev/null >&2 # Good! { cmd1 <<<'my input'; cmd2; } >someFile # Bad.

A quick look at help read tells us that we can specify a file descriptor from which read should read. Bash Redirect Stdout And Stderr To Different Files your complete shell script with multiple echo statements } > 2>&1 | tee -a script.log Reply Link aref ghobadi August 15, 2015, 9:56 amHi thanks a lot Reply Link karthikeyan December Applications

There are always three default files [1] open, stdin (the keyboard), stdout (the screen), and stderr (error messages output The redirection-operator << is used together with a tag TAG that's used to mark the end of input later: # display help cat <

Redirect Standard Output And Error To Dev Null

To prevent an fd from being inherited, close it. # Redirecting only stderr to a pipe. Later we will see how this can be useful. Bash Redirect Standard Output To File I was looking for a solution for the following problem: I want to execute a shell script (both remotely via RSH and locally). Bash Redirect Stderr To Stdout Why?

LOGFILE=script.log echo "This statement is sent to the log file, \"$LOGFILE\"." 1>$LOGFILE echo "This statement is appended to \"$LOGFILE\"." 1>>$LOGFILE echo "This statement is also appended to \"$LOGFILE\"." 1>>$LOGFILE echo "This weblink Outside the whole construct you collect your original standard output (descriptor 3) and your original standard error output (descriptor 1 - through tee) to the normal descriptors (1 and 2), the Continue reading for more on this. I have learned a great deal about redirection. Bash Redirect Stderr To Stdout In Script

exec 3>&- # Close fd 3. Appending redirected output N >> TARGET This redirects the file descriptor number N to the target TARGET. command >/dev/null 2>&1 See also Internal: Illustrated Redirection Tutorial Internal: The noclobber option Internal: The exec builtin command Internal: Simple commands parsing and execution Internal: Process substitution syntax Internal: Obsolete and navigate here If you don't specify a program, the redirection after exec modifies the file descriptors of the current shell.

Browse other questions tagged shell io-redirection openbsd or ask your own question. Bash Redirect Stdout And Stderr To Same File Reply Link Shyam November 18, 2015, 4:10 pmHi, Please tell me how to redirect the output from a script to a log file so that i can save all the details Jan Schampera, 2012/12/16 14:13 I see those additional line coming from the previous echo: [email protected]:~$ echo -e "$tT" A B C [email protected]:~$ It is the additional newline echo adds itself to

A note on style The shell is pretty loose about what it considers a valid redirect.

Put '2>&1' after '>file.log' and it works. –Lars Wirzenius Mar 12 '09 at 9:25 1 Good point, I seem to have been doing this wrong all these years... Password Protected Wifi, page without HTTPS - why the data is send in clear text? ls -l 2>&1 >&3 3>&- | grep bad 3>&- # Close fd 3 for 'grep' (but not 'ls'). # ^^^^ ^^^^ exec 3>&- # Now close it for the remainder of Bash Redirect Stdout And Stderr Append To File exec 3<> File # Open "File" and assign fd 3 to it.

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>&-. In the same way, command 2> file will change the standard error and will make it point to file. The tag you use must be the only word in the line, to be recognized as end-of-here-document marker. his comment is here I can only redirect one of the outputs, not both at the same time.

no, do not subscribeyes, replies to my commentyes, all comments/replies instantlyhourly digestdaily digestweekly digest Or, you can subscribe without commenting. Natural construction more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture All about redirection 3.1 Theory and quick reference There are 3 file descriptors, stdin, stdout and stderr (std=standard). The "here document" will do what it's supposed to do, and the * will, too.

because the shell descriptor of the while loop looks like: --- +-----------------------+ standard input ( 0 ) ---->| file | --- +-----------------------+ --- +-----------------------+ standard output ( 1 ) ---->| /dev/pts/5 Now Bash sees > file and thus changes stdout: --- +-----------------------+ standard input ( 0 ) ---->| /dev/pts/5 | --- +-----------------------+ --- +-----------------------+ standard output ( 1 ) ---->| file | the texts "my message" and "Hello again" have been overwritten by the stderr output of the ls commands. no, do not subscribeyes, replies to my commentyes, all comments/replies instantlyhourly digestdaily digestweekly digest Or, you can subscribe without commenting.

It's difficult to tell where the redirects are and whether they're even valid redirects. # This is in fact one command with one argument, an assignment, and three redirects. for real loggin better way is: exec 1>>$LOG_FILE it cause log is allways appended. –Znik Dec 8 '14 at 9:43 2 That's true although it depends on intentions. Next Previous Contents Advanced Bash-Scripting Guide: PrevNext

Chapter 20. Because after 2>&1, we have 2 file descriptors pointing to the same file.

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