My sample code works like this in principle:
1. You said 4-ish invocations per print file. That means that there would
be 4-ish instances of your script running, if I would not use that lock
file in /tmp to detect that another script instance is already dealing with
the print file. So, the script starts, looks for another script's lock
file, if it doesn't find one , it creates own one, waits a bit, checks
again, and if there is no collision (imagine multiple scripts checking and
creating locks at the same time) it waits for the print file to become
stable.
2. The print file is considered stable if it is not changed for the
duration of 3 (I believe) 1 second wait loops. If the file changes, the
loop counter resets and another 3 set of loops goes by. This way, you do
not have to wait for the max possible print time, every time. I imagine
that long or complex document might take long time to print - if we know
that the printing application updates the file at least every few seconds -
we reset the timer at every change, re-starting the count down.
3. File gets sent to a printer when it is considered stable, and then moved
to a backup dir under new name consisting of a time stamp + the original
name. If something goes wrong you can re-print manually. Backed up files
should sort by its date stamp.
4. On exit, the script removes the lock file.
That's about all....if I remember correctly.
I guess, you could call that lock file a semafor if that sounds better.
Alternatively, you could also look for another process instead of keeping
the lock/semafor file, but that would not allow for multiple files printing
correctly at the same file.
I hope that it is little clearer.
-T
On Nov 21, 2017 7:12 PM, "Denis Heidtmann" <denis.heidtm...@gmail.com>
wrote:
> Me looking at kernel software would be no more educational than me reading
> about it in Greek. And I did not think I wanted to debug the spooler,
> whatever that is.
>
> So to get down to the essentials, using only IN_CLOSE_WRITE, I get four
> events (with this particular application printing). For a big print job
> the timespan from the first event to the last is 10 seconds. I can explore
> my two other applications and come up with a maximum (probable) time. Add
> a buffer to that and use that time as a delay prior to printing the file.
> That was my intended approach.
>
> As I understand your approach it is to check the time stamp for the file in
> question, delay 2 seconds, then assume if no change has occurred, the file
> is ready to print. Is this understanding correct? If so, this assumes
> that the driver/application changes the file more frequently than every 2
> seconds. To explore that, I was trying to send the time to the log every
> time I got an icron invocation with the IN_ALL_EVENTS mask. Hence my use
> of that mask and trying to capture the time to the log. This, I hope,
> explains why I wanted to see the result of <echo -n "time: $(stat -c '%Y'
> $1)" >> /home/denis/incronlog.log>, and the question of why no time appears
> in the log. Notice that there are many cases in the log where $1 appears
> to be a filename.
>
> -Denis
>
> On Tue, Nov 21, 2017 at 1:37 PM, Tomas Kuchta <
> tomas.kuchta.li...@gmail.com>
> wrote:
>
> > Of course that you see some/many invocations without any file names when
> > you trigger on all directory events. All sorts of of processes go by all
> > sorts of directories all the time on modern desktop. Not all of them look
> > at files.
> >
> > What your aim is, I believe/hope, to respond to print file write and
> close
> > - and send that file to a printer. Ideally deleting or backing that file
> > away from the print dir. You want to do that reliably and without
> multiple
> > processes acting on any given file.
> >
> > If you want to debug print job spooler, I would suggest to do just that.
> Do
> > exactly what you need to do, keep it simple, and expand from there.
> >
> > If you are curious about kernel interworks, I would suggest to start
> > looking at kernel documentation and source code - it is more systematic
> way
> > of learning. Unfortunately, I am not the right person to have meaningful
> > conversation about kernel and VFS events/triggers. My knowledge is too
> > shallow for that.
> >
> > Good luck,
> > Tomas
> >
> > On Nov 21, 2017 9:44 AM, "Denis Heidtmann" <denis.heidtm...@gmail.com>
> > wrote:
> >
> > > It is fully my intention to use only IN_CLOSE_WRITE in the final
> version.
> > > I currently am using IN_ALL_EVENTS just to see what the print
> > > driver/application is doing. In fact, when I first started working on
> > this
> > > I used just IN_CLOSE_WRITE and saw 4 invocations. That is what sent
> me
> > > exploring.
> > >
> > > Regarding what is in $1, I see what seems to me to indicate a file name
> > in
> > > $1 *sometimes*. Why only sometimes? Here is the test script:
> > > #! /bin/bash
> > > # test of incron
> > > echo -n "time: $(stat -c '%Y' $1)" >> /home/denis/incronlog.log
> > > echo "test: $1 $2" >> /home/denis/incronlog.log
> > >
> > > I get perhaps 270 invocations with IN_ALL_EVENTS. A sampling shows
> some
> > > responses with the file name, but no times:
> > >
> > > test: IN_ACCESS,IN_ISDIR
> > > time: test: IN_CLOSE_NOWRITE,IN_ISDIR
> > > time: test: IN_CLOSE_NOWRITE,IN_ISDIR
> > > time: test: tst1.PLT IN_OPEN
> > > time: time: test: tst1.PLT IN_OPEN
> > > test: tst1.PLT IN_OPEN
> > > time: test: tst1.PLT IN_CLOSE_NOWRITE
> > > time: test: tst1.PLT IN_ACCESS
> > > time: test: tst1.PLT IN_CLOSE_NOWRITE
> > > time: time: test: IN_CLOSE_NOWRITE,IN_ISDIR
> > > test: IN_ACCESS,IN_ISDIR
> > > time: test: tst1.PLT IN_CLOSE_NOWRITE
> > >
> > > There are a number of questions raised by this, but I expect that most
> > can
> > > be explained by the rapid multiple invocations. Does that also explain
> > the
> > > missing times?
> > >
> > > -Denis
> > >
> > >
> > > On Tue, Nov 21, 2017 at 12:23 AM, Tomas Kuchta <
> > > tomas.kuchta.li...@gmail.com
> > > > wrote:
> > >
> > > > $(some command) will simply execute the command and give return
> value.
> > > >
> > > > You do not see any time stamp because you are not giving stat a file.
> > $1,
> > > > in
> > > > your case, doesn't contain file name.
> > > >
> > > > I have asked or suggested before to only use IN_CLOSE_WRITE event.
> That
> > > is
> > > > what you want - run the script after the file/dir was written to and
> is
> > > > closed. Not the other times when you look at it or read the file with
> > > your
> > > > script. Taking those other events off should solve the multiple
> > > invocation
> > > > problem.
> > > >
> > > > I hope it helps,
> > > > Tomas
> > > >
> > > >
> > > > On Nov 20, 2017 5:54 PM, "Denis Heidtmann" <
> denis.heidtm...@gmail.com>
> > > > wrote:
> > > >
> > > > Working my way through the script, trying to understand the behavior.
> > > Here
> > > > is a simple test:
> > > >
> > > > #! /bin/bash
> > > > # test of incron
> > > > echo -n "time: $(stat -c '%Y' $1)" >> /home/denis/incronlog.log
> > > > echo "test: $1 $2" >> /home/denis/incronlog.log
> > > > # sleep 10
> > > >
> > > > It generates what I would expect when executed from the command line:
> > > > ~/scripts/intest.sh examples.desktop:
> > > > time: 1464568514test: examples.desktop
> > > >
> > > > But when invoked by incron the line including the time is empty
> except
> > > for
> > > > the word "time:" The time value is absent.
> > > > time: time: test: IN_ACCESS,IN_ISDIR
> > > > test: IN_CLOSE_NOWRITE,IN_ISDIR
> > > > time: test: IN_ACCESS,IN_ISDIR
> > > > time: test: IN_OPEN,IN_ISDIR
> > > > time: test: IN_OPEN,IN_ISDIR
> > > > etc.
> > > >
> > > > My knowledge of the use of $, (, ", ', and { is lacking, so I
> expect
> > > > that is where the trouble lies.
> > > >
> > > > Is the problem obvious?
> > > >
> > > > Thanks,
> > > > -Denis
> > > >
> > > > On Sun, Nov 19, 2017 at 10:42 PM, Tomas Kuchta <
> > > > tomas.kuchta.li...@gmail.com
> > > > > wrote:
> > > >
> > > > > The script I posted does its own locking, so that other copies
> would
> > > know
> > > > > that it is already running and what file it is serving.
> > > > >
> > > > > See the lock file being created, checked and removed.
> > > > >
> > > > > Tomas
> > > > >
> > > > > On Nov 19, 2017 9:10 PM, "Denis Heidtmann" <
> > denis.heidtm...@gmail.com>
> > > > > wrote:
> > > > >
> > > > > > Your script has things in it that stretch my knowledge of Bash,
> so
> > > > > > understanding what it does is difficult for me.
> > > > > >
> > > > > > I have no experience with file locking. Is this a standard
> > protocol?
> > > > > > Since the print file is created by a Windows print driver, I
> wonder
> > > if
> > > > > the
> > > > > > locking which is described in the ubuntu docs is reliably
> > applicable.
> > > > > >
> > > > > > This is likely a discussion that stretches what is reasonable to
> > > > attempt
> > > > > > via a forum, since I need considerable education.
> > > > > >
> > > > > > I appreciate your efforts. I will play with it in an attempt to
> > > learn
> > > > > what
> > > > > > you are proposing, but do not be surprised if it takes me some
> > time.
> > > > > >
> > > > > > -Denis
> > > > > >
> > > > > >
> > > > > >
> > > > > > On Sat, Nov 18, 2017 at 9:17 PM, Tom <
> tomas.kuchta.li...@gmail.com
> > >
> > > > > wrote:
> > > > > >
> > > > > > > Hi Denis,
> > > > > > >
> > > > > > > Try something like the script below.
> > > > > > > It uses a lock to detect its own invocation as well as multiple
> > > > > > > invocations of self. If it prints it backs up the printed file,
> > so
> > > > you
> > > > > > > should not lose anything, should things go south.
> > > > > > >
> > > > > > > Note: I did not properly test it. So, give it good pass over
> and
> > > test
> > > > > > > it before calling it a day. As I said, it should not loose any
> > > print
> > > > > > > files and you should know if it prints.
> > > > > > >
> > > > > > > Please insert your own print command instead of the echo "" and
> > > > > > > redirect the output to a log file or /dev/null so it does not
> end
> > > up
> > > > > > > with incron.
> > > > > > >
> > > > > > > Beware of broken script lines by the email.
> > > > > > >
> > > > > > > I hope that it works as intended or as an example,
> > > > > > > Tomas
> > > > > > >
> > > > > > > #!/bin/bash
> > > > > > > ##########################################
> > > > > > > # This command submits a file to print
> > > > > > > # It is triggered by incron and tries to
> > > > > > > # gracefully deal with multiple incron invocations
> > > > > > > # and waits for file to be closed by the
> > > > > > > # print application.
> > > > > > > # Example incron line:
> > > > > > > # printDirToMonitor IN_CLOSE_WRITE submitPrinterJob.bash $#
> > > > > > > ##########################################
> > > > > > > lockDir=/tmp/
> > > > > > > lockFileBaseName=/tmp/submitPrinterJob
> > > > > > > thisPid=$$
> > > > > > > fileToPrint=$1
> > > > > > > printedFilesDir=/home/$USER/printedFilesDir
> > > > > > > mkdir -p $printedFilesDir
> > > > > > >
> > > > > > > searchLockPattern="${lockFileBaseName}_${fileToPrint}_*.lock"
> > > > > > > myLockFileName="${lockFileBaseName}_${
> > > fileToPrint}_${thisPid}.lock"
> > > > > > >
> > > > > > > # check if the file to print is still there
> > > > > > > if [ -e $fileToPrint ]; then
> > > > > > > # Check if another script is running and serving this file
> > > > > > > # Issue lock if not
> > > > > > > c=0
> > > > > > > while (( $c < 2 )); do
> > > > > > > if [ ! -e $searchLockPattern ]; then
> > > > > > > # Cannot see any other process'lock
> > > > > > > touch $myLockFileName
> > > > > > > else
> > > > > > > # there is a lock
> > > > > > > if [ ! -e $myLockFileName ]; then
> > > > > > > # the lock is not mine --> exit without printing,
> > > > > > > # make sure not to leave own lock, in case it take time
> > to
> > > > > > > # show up
> > > > > > > rm -f $myLockFileName
> > > > > > > exit 0
> > > > > > > fi
> > > > > > > fi
> > > > > > > # There should be a lock and mine --> do nothing , just
> wait
> > > > > > > c=$(( $c + 1 ))
> > > > > > > sleep 2
> > > > > > > done
> > > > > > > # if I got here I got a lock --> send the file to printer
> > > > > > > if [ ! -e $fileToPrint ]; then
> > > > > > > echo "WARNING: File $fileToPrint disapeared"
> > > > > > > else
> > > > > > > echo "Printing file $fileToPrint"
> > > > > > > # backing up and removing printed file
> > > > > > > mv $fileToPrint $printedFilesDir
> > > > > > > sleep 1
> > > > > > > # removing lock file
> > > > > > > rm -f $myLockFileName
> > > > > > > fi
> > > > > > > fi
> > > > > > > exit 0
> > > > > > > ##########################################
> > > > > > >
> > > > > > > On Sat, 2017-11-18 at 15:01 -0800, Denis Heidtmann wrote:
> > > > > > > > It turns out that the multiple file closings is at least
> > > partially
> > > > > > > > attributable to the application, since another application
> had
> > > two
> > > > > > > > closings
> > > > > > > > rather than four. Using the application with the four
> > closings I
> > > > > > > > tried
> > > > > > > > again with a much more complicated drawing. This slowed down
> > the
> > > > > > > > writing
> > > > > > > > of the print file to 10 seconds. Those 10 seconds were taken
> > up
> > > > > > > > mostly
> > > > > > > > between the first and second closing (4 sec.) and the third
> and
> > > > > > > > fourth (6
> > > > > > > > sec.) I may need to put a delay at the start of my printing
> > > script
> > > > > > > > so it
> > > > > > > > does not try to print an incomplete file.
> > > > > > > >
> > > > > > > > An aside: The "masks" in the incrontab are separated by
> comas
> > > but
> > > > no
> > > > > > > > spaces are allowed.
> > > > > > > >
> > > > > > > > Nothing turns out as simple as it appears initially.
> > > > > > > >
> > > > > > > > -Denis
> > > > > > > >
> > > > > > > > On Fri, Nov 17, 2017 at 11:38 PM, Tom <
> > > > tomas.kuchta.li...@gmail.com>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > >
> > > > > > > > > I am glad you worked it out. Well done.
> > > > > > > > >
> > > > > > > > > Darn fast computers!!
> > > > > > > > >
> > > > > > > > > -T
> > > > > > > > >
> > > > > > > > > On Fri, 2017-11-17 at 18:04 -0800, Denis Heidtmann wrote:
> > > > > > > > > >
> > > > > > > > > > On the "Create": this convinces me that I should take up
> > > > > > > > > > drinking
> > > > > > > > > > coffee,
> > > > > > > > > > so some stronger brain stimulant. Dumb.
> > > > > > > > > >
> > > > > > > > > > On the multiple entries, I think the issue is that my
> test
> > > > script
> > > > > > > > > > is
> > > > > > > > > > very
> > > > > > > > > > short and fast. I added a sleep 10 and I get only one
> > > > entry--the
> > > > > > > > > > first
> > > > > > > > > > one. Apparently the print driver (or the program calling
> > it)
> > > > > > > > > > closes
> > > > > > > > > > the
> > > > > > > > > > file multiple times. I added $% to the incrontab file
> and
> > %2
> > > > to
> > > > > > > > > > the
> > > > > > > > > > script
> > > > > > > > > > (but w/o the sleep in my script) I got:
> > > > > > > > > >
> > > > > > > > > > test1 create test23 IN_CLOSE_WRITE
> > > > > > > > > > test1 create test23.PLT IN_CLOSE_WRITE
> > > > > > > > > > test1 create test23.PLT IN_CLOSE_WRITE
> > > > > > > > > > test1 create test23.PLT IN_CLOSE_WRITE
> > > > > > > > > >
> > > > > > > > > > This behavior of the driver/application seems not the
> best,
> > > but
> > > > > > > > > > there
> > > > > > > > > > is
> > > > > > > > > > nothing to be done about it. I assume that my printing
> > > script
> > > > > > > > > > will
> > > > > > > > > > take
> > > > > > > > > > sufficient time it will not matter.
> > > > > > > > > >
> > > > > > > > > > I recorded the times associated with the four log
> entries.
> > > It
> > > > > > > > > > was
> > > > > > > > > > 347 msec
> > > > > > > > > > overall, with the last step taking most of this time at
> > about
> > > > 300
> > > > > > > > > > msec. So
> > > > > > > > > > my anticipation that the multiple writes/closing will not
> > > > matter
> > > > > > > > > > seems
> > > > > > > > > > reasonable. Let's hope so.
> > > > > > > > > >
> > > > > > > > > > Thanks again for the suggestion.
> > > > > > > > > >
> > > > > > > > > > -Denis
> > > > > > > > > >
> > > > > > > > > > On Fri, Nov 17, 2017 at 2:02 PM, Tomas Kuchta
> > > > <tomas.kuchta.lists
> > > > > > > > > > @gma
> > > > > > > > > > il.com>
> > > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > If I recall incron details correctly, you get multiple
> > > > entries
> > > > > > > > > > > in
> > > > > > > > > > > your log
> > > > > > > > > > > because you run your script multiple times at different
> > > > events:
> > > > > > > > > > > IN_CLOSE_WRITE,IN_NO_LOOP
> > > > > > > > > > >
> > > > > > > > > > > Your other question: You see "create" in your log
> because
> > > > that
> > > > > > > > > > > is
> > > > > > > > > > > what your
> > > > > > > > > > > echo command puts there in your script.
> > > > > > > > > > >
> > > > > > > > > > > -Tomas
> > > > > > > > > > >
> > > > > > > > > > > On Nov 17, 2017 11:47 AM, "Denis Heidtmann"
> > > > <denis.heidtmann@gm
> > > > > > > > > > > ail.
> > > > > > > > > > > com>
> > > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > I have pursued Tomas' advice to use incron to
> > automatically
> > > > > > > > > > > send
> > > > > > > > > > > files
> > > > > > > > > > > written by the win2k print driver to the printer. I
> have
> > > > > > > > > > > everything down
> > > > > > > > > > > to one issue. To test, I have a simple script
> > (intest.sh)
> > > > that
> > > > > > > > > > > just sends
> > > > > > > > > > > the event responded to to a log file:
> > > > > > > > > > >
> > > > > > > > > > > #! /bin/bash
> > > > > > > > > > > # test of incron
> > > > > > > > > > > echo "tes1 create " $1 >> /home/denis/incronlog.log
> > > > > > > > > > >
> > > > > > > > > > > The incron table is:
> > > > > > > > > > >
> > > > > > > > > > > /home/denis/win2kfiles/Print_files
> > > IN_CLOSE_WRITE,IN_NO_LOOP
> > > > > > > > > > > /home/denis/scripts/intest.sh $#
> > > > > > > > > > >
> > > > > > > > > > > The resulting log is:
> > > > > > > > > > >
> > > > > > > > > > > tes1 create test12
> > > > > > > > > > > tes1 create test12.PLT
> > > > > > > > > > > tes1 create test12.PLT
> > > > > > > > > > > tes1 create test12.PLT
> > > > > > > > > > >
> > > > > > > > > > > It generates multiple entries for one file added (i.e.,
> > one
> > > > > > > > > > > print
> > > > > > > > > > > command). I added IN_ONESHOT to the incrontab:
> > > > > > > > > > >
> > > > > > > > > > > /home/denis/win2kfiles/Print_files
> > > > > > > > > > > IN_CLOSE_WRITE,IN_ONESHOT,IN_NO_LOOP
> > > > > > > > > > > /home/denis/scripts/intest.sh $#
> > > > > > > > > > >
> > > > > > > > > > > I still got multiple entries in the log.
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Questions:
> > > > > > > > > > > Why does the log not say "close" instead of "create"?
> > > > > > > > > > > Why four entries?
> > > > > > > > > > > What might the result be when the script intest.sh is
> > > > replaced
> > > > > > > > > > > by
> > > > > > > > > > > one that
> > > > > > > > > > > prints and deletes the files? Will it be called 4
> times
> > in
> > > > > > > > > > > rapid
> > > > > > > > > > > succession?
> > > > > > > > > > >
> > > > > > > > > > > Any suggestions for testing further?
> > > > > > > > > > >
> > > > > > > > > > > Thanks,
> > > > > > > > > > > -Denis
> > > > > > > > > > > _______________________________________________
> > > > > > > > > > > PLUG mailing list
> > > > > > > > > > > PLUG@pdxlinux.org
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> > > > > > > > > > > _______________________________________________
> > > > > > > > > > > PLUG mailing list
> > > > > > > > > > > PLUG@pdxlinux.org
> > > > > > > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > > > > > > >
> > > > > > > > > > _______________________________________________
> > > > > > > > > > PLUG mailing list
> > > > > > > > > > PLUG@pdxlinux.org
> > > > > > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > > > > > _______________________________________________
> > > > > > > > > PLUG mailing list
> > > > > > > > > PLUG@pdxlinux.org
> > > > > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > > > > >
> > > > > > > > _______________________________________________
> > > > > > > > PLUG mailing list
> > > > > > > > PLUG@pdxlinux.org
> > > > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > > > _______________________________________________
> > > > > > > PLUG mailing list
> > > > > > > PLUG@pdxlinux.org
> > > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > > >
> > > > > > _______________________________________________
> > > > > > PLUG mailing list
> > > > > > PLUG@pdxlinux.org
> > > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > > >
> > > > > _______________________________________________
> > > > > PLUG mailing list
> > > > > PLUG@pdxlinux.org
> > > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > >
> > > > _______________________________________________
> > > > PLUG mailing list
> > > > PLUG@pdxlinux.org
> > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > > _______________________________________________
> > > > PLUG mailing list
> > > > PLUG@pdxlinux.org
> > > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > > >
> > > _______________________________________________
> > > PLUG mailing list
> > > PLUG@pdxlinux.org
> > > http://lists.pdxlinux.org/mailman/listinfo/plug
> > >
> > _______________________________________________
> > PLUG mailing list
> > PLUG@pdxlinux.org
> > http://lists.pdxlinux.org/mailman/listinfo/plug
> >
> _______________________________________________
> PLUG mailing list
> PLUG@pdxlinux.org
> http://lists.pdxlinux.org/mailman/listinfo/plug
>
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PLUG mailing list
PLUG@pdxlinux.org
http://lists.pdxlinux.org/mailman/listinfo/plug
