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The following command will create a pdf file under ~/PDF/:

enscript -B -P PDF  bloom.c

I want to move the output pdf file here 

mv "`ls -dtr1 ~/PDF/* | tail -1`" .

But I can't run the mv command immedately follow the enscript command, because enscript sends the input file to the printer PDF, and returns immediately before the printer finishes creating a pdf file.

A very bad solution is to insert the following command between the two commands

sleep 5

It is bad because I don't know how long I shall wait.

Note that I know there is other better way to do the same thing without having to run the mv command after enscript, but I just wonder if there is any way to make enscript block till the printer finishes its job? I remember having similar thoughts for other commands besidesenscript. I am assuming that enscript doesn't provide such an option, so would be interested in whether bash or other program can make that happen. Signal handling might be a solution, but I don't know which signal to catch.

Tim
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  • Hi @Tim, i would suggest that you try `wait ` instead of `sleep` https://stackoverflow.com/questions/13296863/difference-between-wait-and-sleep –  Sep 20 '18 at 20:45
  • Does `lpstat -p PDF` show something different if you run it while the printer is generating the output file vs. after it finishes generating the file? If so, it may be possible to write a shell script to do what you need. – Mark Plotnick Sep 20 '18 at 20:56
  • @Goro `enscript -B -P PDF code/bloom.c & wait $!` will not work, because the job of `enscript` returns immediately. – Tim Sep 20 '18 at 22:36
  • @Tim. I would suggest that you change your approach. Instead of `sleep` let the script sense when the PDF file is really exist in the path then move it. Use `if then statement` –  Sep 20 '18 at 23:00
  • enscript [just runs the lpr command](http://git.savannah.gnu.org/gitweb/?p=enscript.git;a=blob;f=src/prt_lpr.c;hb=HEAD), along with any options that you pass to it. I don't know offhand how to make cups not spool, that is, how to make the `lpr` command only exit after the printer driver has run to completion. If you don't get an answer here, you might consider asking the more general question about the cups `lpr` command. – Mark Plotnick Sep 24 '18 at 15:49

1 Answers1

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As this is too large to put into a comment, have you tried checking whether any files in the ~/PDF directory are still open while they're begin spooled by using lsof (LiSt Open Files)?

Add this code snippet after your enscript -B -P PDF bloom.c:

# Go into endless loop and break when all files in */PDF/* are closed.
while :
do
    if ! [[ `lsof | grep /PDF/` ]]
    then
        break
    fi
    sleep 1
done

and before the

mv "`ls -dtr1 ~/PDF/* | tail -1`"

This way you lose only 1 second...

For more info:

  • lsof will list all currently open files
  • the obligatory man lsof will give you even more details.

;-)

Fabby
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