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Full Discussion: Variables and math in Old skool Bourne Shell
Top Forums UNIX for Dummies Questions & Answers Variables and math in Old skool Bourne Shell Post 302677229 by mr.rhtuner on Wednesday 25th of July 2012 06:53:46 PM
Old 07-25-2012
Variables and math in Old skool Bourne Shell
Hey everybody, I've been searching google and these forums and have found some solutions to the issues I've been having today within the OLD Bourne Shell. I am following chapter 6 of the Guide to Unix using Linux 4th Edition.

I am working on some basic calculations with variables in the BASH SHELL and doing the same within the Bourne Shell with modifications.

In BASH, I did the following:

Code:
let X=10+2*7
Type echo $X and press Enter. You see 24 on the screen.

Now I realize that the bourne shell does NOT have LET as a command, and I need to use expr.

I was able to get the math to work, by doing the following:

Code:
$ expr 10 + 2 '*' 7
24 is the answer.

But how do I incorporate the variable of X into this?

I tried:

Code:
$ X=%((10 + 2 '*' 7))
but get the error: synatx error: 'X=% unexpected


Anybody mind giving me an idea what I am doing wrong?
 

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LEARN ABOUT MOJAVE

cpanplus::shell::default::plugins::source5.18

CPANPLUS::Shell::Default::Plugins::Source(3pm)		 Perl Programmers Reference Guide	    CPANPLUS::Shell::Default::Plugins::Source(3pm)

NAME

       CPANPLUS::Shell::Default::Plugins::Source - read in CPANPLUS commands

SYNOPSIS

	   CPAN Terminal> /source /tmp/list_of_commands /tmp/more_commands

DESCRIPTION

       This is a "CPANPLUS::Shell::Default" plugin that works just like your unix shells source(1) command; it reads in a file that has commands
       in it to execute, and then executes them.

       A sample file might look like this:

	   # first, update all the source files
	   x --update_source

	   # find all of my modules that are on the CPAN
	   # test them, and store the error log
	   a ^KANE$'
	   t *
	   p /home/kane/cpan-autotest/log

	   # and inform us we're good to go
	   ! print "Autotest complete, log stored; please enter your commands!"

       Note how empty lines, and lines starting with a '#' are being skipped in the execution.

BUG REPORTS

       Please report bugs or other issues to <bug-cpanplus@rt.cpan.org<gt>.

AUTHOR

       This module by Jos Boumans <kane@cpan.org>.

COPYRIGHT

       The CPAN++ interface (of which this module is a part of) is copyright (c) 2001 - 2007, Jos Boumans <kane@cpan.org>. All rights reserved.

       This library is free software; you may redistribute and/or modify it under the same terms as Perl itself.

SEE ALSO

       CPANPLUS::Shell::Default, CPANPLUS::Shell, cpanp

perl v5.18.2							    2014-01-06			    CPANPLUS::Shell::Default::Plugins::Source(3pm)
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