How can I reduce count value in shell scripting

[Saraswathy_1]

I have set variable in script in between want to reduce the count by one.

Please advice.

[Peter Godron]

Hi,
man expr

a=10
a=`expr $a - 1`
echo $a
9

[James R. Ferguson]

Hi:

Using the shell's arithmetic:

# X=10;X=$((X - 1));echo ${X}

Regards!

...JRF...

[Bill Hassell]

Another way which is easier to read is:

let MYVAR=$MYVAR-1

You can use normal math symbols in the arithmetic let statement:

let MYVAR=$MYVAR*3
let MYVAR=$VAR2-$VAR3+1

[Ninad_1]

There are several ways as mentioned above as well as

echo $MYVAR - 1 | bc

If you want to store in a variable
result=$(echo $MYVAR - 1 | bc)


Regards,
Ninad

[Glen R. Bartlett]

In the superior Scripting language of Perl :) you can use the same pre-fix and post-fix operators as C/C++.

a++; increase by 1
a--; decrease by 1

[Peter Nikitka]

Hi,

I'm missing this format:

typeset -i var=12
((var-=1))

print $var says 11

mfG Peter

[Glen R. Bartlett]

csh can also use the C type operators

--------------
#!/usr/bin/csh

@ a = 4
@ a--
echo "$a"
@ a += 2
echo "$a"
--------------
output:
3
5

[Rodney Hills]

You can say-

(( MYVAR=MYVAR - 1 ))
or equivalent
let "MYVAR=MYVAR - 1"

Note that you don't need $ in front of variables names since the shell is doing the arithmetic calculations.

HTH

-- Rod Hills

[Saraswathy_1]

thanks