[NTLUG:Discuss] Simple bash shell question

[. Daniel]

Wow!  Exceptionally helpful information.  I also forsee another problem:

If the number of files I select for processing exceeds 100, I'm sort of in 
trouble.  I know there is definitely a better way to manage what I'm trying 
to do.  But the answer doesn't seem to be jumping into my brain right away.

Anyway, here's what I have so far:

----
#!/bin/sh
fcount=0
for filename in $( ls -1 *.mpg )
do
    fcount=$(expr $fcount + 1 )
done
increment=$(expr 100 / $fcount)

(
loopcount=0
for filename in $( ls -1 *.mpg )
do
    loopcount=$(expr $loopcount + 1)
    echo $(expr $loopcount \* $increment)
    echo "# Processing $filename"
    sleep 2
done
) |
zenity --progress --title="Converting files" --text="Processing ..." 
--percentage=0
----

Works pretty cool if the number of files is less than 100.  I haven't tried 
more than 100 yet, but the numbers don't look good since the math is all 
integer.  So if the result of the division is less than 1 it is just 0.  So 
when it is trying to echo the current percentage of completion, it will 
always read 0 and the progress bar will never advance.  There has to be a 
better way... I'll probably figure it out eventually (probably something 
along the lines of multiplying something by 100 first or something) but 
nothing occurs to me yet... so it's a race!  Who is smarter than I am - 
speed of email?


>
>The line:
>
>     for filename in $( ls -1 *.mpg )
>
>will split a file name if it has a space in it.
>
>See
>
>     http://tinyurl.com/32wspa
>
>Ed
>
>
>. Daniel wrote:
> > I found the culprit and a new/better way to do it.
> >
> > As it turns out, doing the pipe thing forks another shell process and 
so
> > the scope of the variables is different.  So here's what I did to 
overcome
> > that:
> >
> > ----
> > #!/bin/sh
> > fcount=0
> > for filename in $( ls -1 *.mpg )
> > do
> >     fcount=$(expr $fcount + 1 )
> >     echo $fcount
> > done
> > echo $fcount
> > ----
> >
> > It now behaves as I intended.  Eventually, this will become a Nautilus
> > script and I will replace "ls -1 *.mpg" with "echo
> > $NAUTILUS_SCRIPT_SELECTED_FILE_PATHS" to get a list of selected 
filename.
> > I need to count the filenames so I can then calculate a percentage 
value
> > for completion and pass it to zenity so I can have a progress meter 
dialog.
> >
> > So, count first, then process, all the while echoing the progress 
values to
> > zenity so I can see how far along it has gone.  Crazy right?
> >
> >
> >> . Daniel wrote:
> >>
> >>> This is probably so elementary that maybe I shouldn't bother asking, 
but
> >>> I'd like to know.
> >>>
> >>> Given the following:
> >>> ----
> >>> #!/bin/sh
> >>> fcount=0
> >>> ls -1 *.mpg | while read filename ; do
> >>>    fcount=$(expr $fcount + 1)
> >>>    echo $fcount
> >>> done
> >>> echo $fcount
> >>> ----
> >>>
> >>> why do I get the following output?
> >>> ----
> >>> [daniel at alpha ~]$ test.sh
> >>> 1
> >>> 2
> >>> 3
> >>> 4
> >>> 0
> >>> ----
> >>>
> >>> I would expect:
> >>> 1
> >>> 2
> >>> 3
> >>> 4
> >>> 4
> >>>
> >>> Where is my thinking broken?
> >>>
> >>>
> >> Daniel
> >> It is obviously a scope issue - but to test this a little further, I 
set
> >> the initial value to 2 and got the following results:
> >> 3
> >> 4
> >> 5
> >> 2
> >> ... of course I only have 3 mpg files. No help perhaps.
> >> Regards
> >> Fred James
> >>
> >>
> >> _______________________________________________
> >> http://www.ntlug.org/mailman/listinfo/discuss
> >
> > _________________________________________________________________
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よ
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> >
> >
> > _______________________________________________
> > http://www.ntlug.org/mailman/listinfo/discuss
> >
>
>_______________________________________________
>http://www.ntlug.org/mailman/listinfo/discuss

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