Re: bash NEWBIE I/O and I/O redirection problems

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

i agree with what der.hans advised.

With long running programs and the risk that they get aborted by Ctrl+C,
i would also advise "tee" option -i. It makes sure that all output gets
written to the file before "tee" aborts.

  ... | tee -a -i ~/my_logfile

As long as the logfile path is a single word (i.e. without blanks or
such), you may put the whole "tee" run into a variable to get less
ugly code:

  # Define redirection command
  tee="tee -a -i $HOME/my_logfile"

  # Remove old log
  rm $HOME/my_logfile

  # Do the work
  while ...
    ...
    echo "Block count: "$blocks | $tee


(The variable $tee does not work with "~" instead of "$HOME".)


> # need code here for /dev/sr0 to be "ready" 

You could use xorriso to do the waiting (and the tray loading if
needed):

  xorriso -outdev /dev/sr0

In the good old times, one could also do

  eject -t

or

  dd if=/dev/sr0 count=1 of=/dev/null

But a kernel regression between 2.6 and 3.16 spoiled the feature that
the tray goes in on the first read attempt and that reading waits until
the drive reports to be ready.


---------------------------------------------------------------------
Unrelated nitpicking:

> xorriso -indev /dev/sr0 -data_cache_size 512 1024 -check_media data_to=$FILENAME 

I wonder why you need 1 GiB of memory cache. It will only be of help
while -indev loads the directory tree, which i assume is much smaller
than 1 GiB.
128 MiB would be:  -data_cache_size 64 1024

You may avoid loading the directory tree by using -outdev instead of
-indev:

  xorriso -outdev /dev/sr0 -check_media use=outdev data_to=$FILENAME --

The parameter range of -check_media should be ended by "--", so that
one can later append further xorriso commands after -check_media.

Maybe you should check for xorriso failure:

  xorriso ...

  if test "$?" = 0
  then
    echo "xorriso run succeeded"
  else
    echo
    echo "   XORRISO RUN FAILED !"
    echo
  fi


Have a nice day :)

Thomas