Adding numbers in shell script (easy quest)

[Brien M. Oberstein]

Here's an easy question, how do you add numbers in a shell script?
I want to hav a script which does something like echo '$2+20'
ie add 20 to the value of the argument $2

-brien

[Mark Thomas]

br...@cco.caltech.edu (Brien M. Oberstein) writes:

: Here's an easy question, how do you add numbers in a shell script?

: I want to hav a script which does something like echo '$2+20'
: ie add 20 to the value of the argument $2

In the c-shell ( csh ) :

(btw, variable names must begin with a letter...)

set $foo = 2;
@ foo = $foo + 20;
echo $foo;

(produces: 22)

In the bourne shell ( sh ) :

foo=2;
foo=`expr $foo + 20`;
echo $foo;

(produces: 22)

Hope it helps,

-mark
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:) :) :)

[Johan Svensson]

Try this:

echo `expr $2 + 20`

PLEASE NOTE: The "'" should be typed the other way around
("accent grave" in French)!
Unfortunately, my News editor wouldn't let me
do that trick...

Regards,
__________________________________________________________
Johan Svensson Email: jo...@ECSDG.lu.se
Tel: +46-46-104505
EkonomiCentrum Software Development Group, Lund University
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[Douglas Bridgens]

Johan Svensson (jo...@ecsdg.lu.se) wrote:

: In article r...@gap.cco.caltech.edu, br...@cco.caltech.edu (Brien M. Oberstein) writes:
: >Here's an easy question, how do you add numbers in a shell script?
: >I want to hav a script which does something like echo '$2+20'
: >ie add 20 to the value of the argument $2
: >
: >
: >-brien

: Try this:

: echo `expr $2 + 20`

This works in the ksh, not sure about others :

echo $(($2 + 20))

unlike the example about this doesn't create a new process.

cheers

Doug

[Paul Stephen Borile]

br...@cco.caltech.edu (Brien M. Oberstein) writes:

Try "man expr". You will find out that it is as simple as :

b=`expr $2 + 20`
echo $b

expr(1) also does a lot of other things.

-Paul
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[David Thomas Richard Given]

In article <2vmn14$r...@gap.cco.caltech.edu>,

Kludge time!

Try:

a=`bc $2 + 20`

--
__ _ _ _ _ | GCS -d+(?)(++) p(-+)(---) c++++ !l+(+)
| \ /_\\ /| | \ / |\ /|_ |\ | | u++ e*(++) m*(++) s !n h+(++) f+ g+
|_/ | | V | |_/ \_| | V |_ | \| | w+(+++) t--(+) r y? (Archimedes owner)
dt...@st-andrews.ac.uk | ***In search of better V's***

[Tim Love]

dt...@st-andrews.ac.uk (David Thomas Richard Given) writes:

>In article <2vmn14$r...@gap.cco.caltech.edu>,
>Brien M. Oberstein <br...@cco.caltech.edu> wrote:
>>Here's an easy question, how do you add numbers in a shell script?
>>I want to hav a script which does something like echo '$2+20'
>>ie add 20 to the value of the argument $2

>Kludge time!

>Try:

>a=`bc $2 + 20`

And the korn shell has a builtin called 'let' to do arithmetic.