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Division, Addition, Subtraction and Multiplication
Posted: Wed 17 Feb 2016, 18:05
by LazY Puppy
Hi.
This works:
STEPS=$(( $SECONDS / 100 ))
Also this: STEP=
$(( $STEP + 2 ))
This won't work:
STEPS=$(( $SECONDS * 60 ))
How to do a multiplication in bash?
Thanks
Edit:
Sorry, the problem was a typo I found yet.
So this works of course also:
STEPS=$(( $SECONDS * 60 )) 
Posted: Thu 18 Feb 2016, 02:00
by slavvo67
Maybe this link will help. Different format but it appears to work.
http://www.murga-linux.com/puppy/viewtopic.php?t=101416
Re: Division, Addition, Subtraction and Multiplication
Posted: Thu 18 Feb 2016, 02:36
by MochiMoppel
LazY Puppy wrote:This won't work: STEPS=$(( $SECONDS * 60 ))
Why not?
So this works of course also: STEPS=$(( $SECONDS * 60 ))
"Of course"? Where is the difference? I understand that you edited your post, but if you also edited your typo the whole post becomes confusing.
BTW: Depending on what you want to calculate your example might produce unexpected results. What do you expect as a result for variable STEP in following example? "Of course" 300 I hope...
Code: Select all
#!/bin/bash
SECONDS=2
sleep 3
STEP=$(( $SECONDS * 60 ))
echo $STEP
Re: Division, Addition, Subtraction and Multiplication
Posted: Thu 18 Feb 2016, 03:40
by LazY Puppy
MochiMoppel wrote:LazY Puppy wrote:This won't work: STEPS=$(( $SECONDS * 60 ))
Why not?
So this works of course also: STEPS=$(( $SECONDS * 60 ))
"Of course"? Where is the difference? I understand that you edited your post, but if you also edited your typo the whole post becomes confusing.
BTW: Depending on what you want to calculate your example might produce unexpected results. What do you expect as a result for variable STEP in following example? "Of course" 300 I hope...
Code: Select all
#!/bin/bash
SECONDS=2
sleep 3
STEP=$(( $SECONDS * 60 ))
echo $STEP
No, I did NOT edit my typo.
The typo was in the script from where these examples has been taken.
The problem was as SECONDS was created this way::
SECONDS=$(( $SECONDS1 + $SECONDS2 ))
But I had used
seconds1 and
seconds2 above in the related script.
SECONDS1 (seconds1) was build from the minutes of a time variable return (mp3 tag) (e.g. 03:47)
I just rebuilt minutes plus seconds to just seconds to have a <hscale> widget moving from the left to the right of the GUI to give an optical impression of current song position (I'd created my first Audio Player using GtkDialog; a simple one, just directory and files based).
So
seconds1 is different to
SECONDS1.
That's just all.
Probably Flash could just remove this topic?
Posted: Thu 18 Feb 2016, 04:42
by MochiMoppel
I'm not much interested in your typo. I only wanted to draw your kind attention to the fact that $SECONDS is a special bash variable like $1, $LINENO or $PWD. You should never use these names for your own variables unless you know what you are doing.
Posted: Thu 18 Feb 2016, 06:38
by LazY Puppy
MochiMoppel wrote:I'm not much interested in your typo. I only wanted to draw your kind attention to the fact that $SECONDS is a special bash variable like $1, $LINENO or $PWD. You should never use these names for your own variables unless you know what you are doing.
Ok, I did not know about $SECONDS being a special bash variable. Going to change this immediately.
Thanks.