Can I use a environment variable as a number

[Pascal Kouknas]

What I would like it to do is.

#export SEQ=21003
#echo $SEQ
#21003

#export var33=$SEQ+1
#echo $var33
#21004


What it is doing is:

#export var33=$SEQ+1
#echo $var33
#21003+1


Is there a simple way to do this. Treat it as a number ?

[Sridhar Bhaskarla]

You can do it by using command substitution

Try this way

export var33=$(($SEQ + 1))

-Sri

[Sajid_1]

hello,

the best way for doing arithmatic calculation is 'expr'. Chcek:
# man expr

this way you can define the numbers..

[Michael Tully · Accepted solution]

Try using 'expr'

$ var33=`expr $SEQ + 1`
$ echo $var33
21004

[A. Clay Stephenson]

As long as this is the POSIX or Korn shell, you can do it within the shell and it is more efficient than calling expr because no fork/exec's are necessary.

var33=$((${SEQ} + 1))
or
let var33=${SEQ}+1

THese two statements are equivalent but the first form is really the preferred syntax because it is very tolerant of spaces. It is also easier to group complex statements within paren's.