Comments on: Let Bash do the math: Doing calculations using that bash http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/ syslogd goes web 2.0 Sun, 27 Dec 2009 12:55:55 +0000 http://wordpress.com/ hourly 1 By: E.M. http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-12878 E.M. Sun, 27 Dec 2009 12:55:55 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-12878 Really? ~$ echo $((5*(10+2))) 60 ~$ echo $((5*\(10+2\))) bash: 5*\(10+2\): syntax error: operand expected (error token is "\(10+2\)") Really?

~$ echo $((5*(10+2)))
60
~$ echo $((5*\(10+2\)))
bash: 5*\(10+2\): syntax error: operand expected (error token is “\(10+2\)”)

]]> By: jaenmedina http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-12877 jaenmedina Sun, 27 Dec 2009 12:47:51 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-12877 If you want to evaluate multiple math expressions the parentheses must be escaped. This is necessary so the shell will not treat them as a reference to a sub-shell. For example, if you want to evaluate 100*(50-16), you will have to write 100*\(50-16\) Hope this helps. Source: Burtch, Ken. Linux Shell Scripting with BASH. Indianapolis, Indiana: Sams Publishing. 2004. Page 95 If you want to evaluate multiple math expressions the parentheses must be escaped. This is necessary so the shell will not treat them as a reference to a sub-shell.
For example, if you want to evaluate 100*(50-16), you will have to write 100*\(50-16\)

Hope this helps.

Source: Burtch, Ken. Linux Shell Scripting with BASH. Indianapolis, Indiana: Sams Publishing. 2004. Page 95

]]> By: Calcoli aritmetici dalla bash di linux « Oracle and other http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-12362 Calcoli aritmetici dalla bash di linux « Oracle and other Tue, 20 Oct 2009 13:12:12 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-12362 [...] operatori supportati sono molti, elencati anche in questo blog, ad esempio ** per calcolare la [...] [...] operatori supportati sono molti, elencati anche in questo blog, ad esempio ** per calcolare la [...]

]]> By: ken http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-11986 ken Thu, 20 Aug 2009 15:07:28 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-11986 Figured it out... it should be ( i=0; while [ $i -ne 5 ]; do echo Increment: $((++i)) ; done ) Figured it out… it should be

( i=0; while [ $i -ne 5 ]; do echo Increment: $((++i)) ; done )

]]> By: ken http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-11985 ken Thu, 20 Aug 2009 14:02:16 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-11985 Why doesn't this increment? ( i=0; while [ $i!=5 ]; do echo Increment: $((++${i})) ; done ) Why doesn’t this increment?

( i=0; while [ $i!=5 ]; do echo Increment: $((++${i})) ; done )

]]> By: E.M. http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-9591 E.M. Mon, 09 Mar 2009 21:00:47 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-9591 Your way will work, but it just looks more complicated. Basically, your way is saying 'do 3+4, then use this like a variable, times this variable by 3 then make it act like another variable'. Where as my way basically does it all in one go. It probably doesn't make much difference either way, but it's just easier to read IMO :-) Your way will work, but it just looks more complicated.

Basically, your way is saying ‘do 3+4, then use this like a variable, times this variable by 3 then make it act like another variable’.

Where as my way basically does it all in one go.

It probably doesn’t make much difference either way, but it’s just easier to read IMO :-)

]]> By: sysblog http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-9590 sysblog Mon, 09 Mar 2009 18:39:20 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-9590 Thanks for sharing that information! I cannot remember where I had my info from but maybe it just was due to a different version of bash. Thanks for sharing that information! I cannot remember where I had my info from but maybe it just was due to a different version of bash.

]]> By: E.M. http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-9587 E.M. Mon, 09 Mar 2009 11:44:17 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-9587 No, it doesn't. ~$ echo $(((3+4)*3)) 21 No, it doesn’t.

~$ echo $(((3+4)*3))
21

]]> By: Juan http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-7964 Juan Tue, 25 Nov 2008 15:35:47 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-7964 where i can find some how to related with advanced operations in bash? where i can find some how to related with advanced operations in bash?

]]> By: sysblog http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-6522 sysblog Wed, 13 Aug 2008 19:02:19 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-6522 as far as I know bash itself only knows about integers. But there's an article that could help you at <a href="http://www.novell.com/coolsolutions/tools/17043.html" rel="nofollow">cool solutions on novell.com</a> that uses bc and a small script. Cheers. as far as I know bash itself only knows about integers. But there’s an article that could help you at cool solutions on novell.com that uses bc and a small script.

Cheers.

]]> By: julien http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-6518 julien Wed, 13 Aug 2008 16:22:35 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-6518 How does it work with decimal number?????? I always get some errors. How does it work with decimal number??????
I always get some errors.

]]> By: suma valluru http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-837 suma valluru Wed, 12 Sep 2007 11:57:31 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-837 hi, arithmetic math is the perfect one in all the math topics... Cheers, Suma valluru --------------------------- www.esumz.com hi, arithmetic math is the perfect one in all the math topics…

Cheers,
Suma valluru
—————————
http://www.esumz.com

]]> By: sysblog http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-727 sysblog Mon, 03 Sep 2007 15:26:15 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-727 Thanks, katm. But be warned that <strong>every single</strong> grouping has to come in double brackets. So for something like $latex (3+4)*3$ it's <code>$(($((3+4))*3))</code>. So for some complex mathematics it would even be easier to use lisp :D But I like the quick and dirty <code>$((2**32))</code> for $latex 2^{32}$ for example. Cheers. Thanks, katm.

But be warned that every single grouping has to come in double brackets. So for something like (3+4)*3 it’s $(($((3+4))*3)). So for some complex mathematics it would even be easier to use lisp :D But I like the quick and dirty $((2**32)) for 2^{32} for example.

Cheers.

]]> By: katm http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/comment-page-1/#comment-726 katm Mon, 03 Sep 2007 15:06:55 +0000 http://sysblogd.wordpress.com/2007/08/26/let-bash-do-the-math-doing-calculations-using-that-bash/#comment-726 Oh now this is just nifty. And as a Linux noob, I think even I can follow it. Just another toy to play with :) Oh now this is just nifty.

And as a Linux noob, I think even I can follow it.

Just another toy to play with :)

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