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Full Discussion: File descriptors, redirecting output, and stdout
Top Forums Shell Programming and Scripting File descriptors, redirecting output, and stdout Post 302675703 by Corona688 on Monday 23rd of July 2012 12:07:51 PM
Old 07-23-2012
Instead of redirecting to 3 and 4 and using 'print -u4', you could've redirected stdout and stderr themselves. with 'exec 1>' and 'exec 2>' respectively, and not modified your print commands at all.

Of course, since you seem to wish to preserve stdout/stderr now, it'd be better to keep stdout/err as is.

A redirection can't cause something to print twice. If you want to print twice, you have to print twice. You can make a function to do so, however, simplifying things for you.

Code:
function output
{
        print "$@" >&3
        [ ! -z "$DEBUG" ] && print "$@"
}

function debug
{
        print "$@" >&4
        [ ! -z "$DEBUG" ] && print "$@" >&2
}

If you want to see the output appear on the screen, run it like DEBUG=1 ./myscript

or export the DEBUG variable in your shell or profile.
Last edited by Corona688; 07-23-2012 at 01:13 PM..
This User Gave Thanks to Corona688 For This Post:
Michael_K
 

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LEARN ABOUT DEBIAN

calibre-debug

CALIBRE-DEBUG(1)						      calibre							  CALIBRE-DEBUG(1)

NAME

       calibre-debug - part of calibre

SYNOPSIS

       calibre-debug  [options]

DESCRIPTION

       Run an embedded python interpreter.

       Whenever you pass arguments to calibre-debug that have spaces in them, enclose the arguments in quotation marks.

OPTIONS

       --version
	      show program's version number and exit

       -h, --help
	      show this help message and exit

       -c, --command
	      Run python code.

       -e, --exec-file
	      Run the python code in file.

       -d, --debug-device-driver
	      Debug the specified device driver.

       -g, --gui
	      Run the GUI with debugging enabled. Debug output is printed to stdout and stderr.

       --gui-debug
	      Run  the	GUI  with a debug console, logging to the specified path. For internal use only, use the -g option to run the GUI in debug
	      mode

       --show-gui-debug
	      Display the specified log file. For internal use only.

       -w, --viewer
	      Run the ebook viewer

       --paths
	      Output the paths necessary to setup the calibre environment

       --migrate
	      Migrate old database. Needs two arguments. Path to library1.db and path to new library folder.

       --add-simple-plugin
	      Add a simple plugin (i.e. a plugin that consists of only a .py file), by specifying the path to the py file  containing  the  plugin
	      code.

       --reinitialize-db
	      Re-initialize the sqlite calibre database at the specified path. Useful to recover from db corruption. You can also specify the path
	      to an SQL dump which will be used instead of trying to dump the database. This can be useful when dumping fails,	but  dumping  with
	      sqlite3 works.

       -p, --py-console
	      Run python console

       -m, --inspect-mobi
	      Inspect the MOBI file(s) at the specified path(s)

       --tweak-book
	      Tweak  the  book (exports the book as a collection of HTML files and metadata, which you can edit using standard HTML editing tools,
	      and then rebuilds the file from the edited HTML. Makes no additional changes to the HTML, unlike a full calibre conversion).

       --test-build
	      Test binary modules in build

SEE ALSO

       The User Manual is available at http://manual.calibre-ebook.com

       Created by Kovid Goyal <kovid@kovidgoyal.net>

calibre-debug (calibre 0.8.51)					   January 2013 						  CALIBRE-DEBUG(1)
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