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The problem statement, all variables and given/known data:
Write a bash shell script that takes as an argument a name. Then your script will ask the user for two numbers. It should then display the name and the sum (addition) and product (multiplication) of the two numbers
I don't know how to get numbers and add them
Relevant commands, code, scripts, algorithms:
echo Please, enter your name
The attempts at a solution (include all code and scripts):
#!/bin/bash
echo Please, enter your name
read NAME
echo "$NAME!"
Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
Sheridan, Brampton Canada, SYST13416 LinuxUNIXOperating Systems
Martin
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Well, numbers often come from string data, for instance if first argument on the command line, "$1". You can read text in from the keyboard and pattern-test it to ensure it is valid text. Bash and ksh support $(( )), which does all sorts of integer arithmetic, e.g., z=$(( $z + 1 )), and if (( )), which allows all sorts of integer tests, e.g., if (( $z < 30 )). I am not sure they have a friendly floating point, probably. Let me google a bit . . . no, bash does not. I use dc or bc to do my floating point calculations within scripts, or move to a more formal language. The text from bc can be tested to see if it is negative, for instance.
[quote=dgpickett;302513199]
But then it might not be ksh portable!
$ echo "(( 1 + 2 ))"
(( 1 + 2 ))
$ echo (( 1 + 2 ))
ksh: syntax error: `((' unexpected That's not "unportable" -- that's simply wrong. BASH and KSH alike agree this is a syntax error, and for good reason:
Produces a string: $((stuff))
Produces no string: ((stuff))
Plain (( )) without the $ is more like a [ ] statement. Try it: if ((0)) ; then echo asdf ; fi
if ((1)) ; then echo asdf ; fi
When you use them in a syntactically valid manner, as their own statement, they're fine: ((k = k + 5))
You also missed my point about k vs $k inside (( )). ((k=k+3)) works, (($k=$k+3)) does not since K gets substituted before anything starts calculating, so you end up trying to assign the value of 3 or something. Just plain variable names don't ever need a $ inside a (( )) expression anyway, why make them more complicated?
I suspected something such, as the sh executable is separate, bigger and newer.
I can never sort out the culture wars between POSIX, AT&T SVR?, LINUX, GNU, BSD and all the prop. players: AIX, Solaris, HP-UX, ???? I know they keep changing the regex, so I have to worry about which library path which program runs under. I want my \< and \> back!
Returning to original question... Here is one way to get a number...
$ cat getn
#! /usr/bin/ksh
printf "Enter a number - "
read number
printf "you entered %d \n" $number
exit 0
$
$
$ ./getn
Enter a number - 77
you entered 77
$
I think you should be able to expand it to get 2 numbers. And you seem to have a complete discussion on adding them.
Doesn't get it outside, k=$(( $k + 3 )), so that is not an issue.
I like 11 as the right answer, so $ is necessary? Mult takes precedence over + ? Or left to right, it should be 15. Ugly! I always use paren. no priority applicable.
Longer, less intuitive(some k's need $ and some don't), and has many unintended side-effects. ((k=k+5)) will work. Failing that, why not just use expr?
I tested the syntax on the absolute 'worst' ksh I could find.
