Problems with expr

benu302000 · #1 (**permalink**) 06-28-2005

I'm writing a unix script that simply does some basic command line stuff for a whole lot of similar directories (ls *.dat > foo.bar). Its my first script ever, and its going ok, except I can't, for the life of me, figure out how to get arithmetic to work in the script.

FIVE=5
MY_NUMBER='expr $FIVE + 3'
echo $MY_NUMBER

even this simple script either outputs "expr $FIVE + 3" at the command line, or fails utterly. Any Ideas? I'm writing it for the bourne shell, on a SOLARIS machine.

Perderabo · #2 (**permalink**) 06-28-2005

Use backquotes (`), not single quotes (').

benu302000 · #3 (**permalink**) 06-28-2005

Ah, Didn't even realized those existed until now, thank you

sssow · #4 (**permalink**) 06-28-2005

I prefer to use let in this case as follows
five=5
let five=$five+3
echo $five

Perderabo · #5 (**permalink**) 06-28-2005

sh on Solaris has no built in arithmetic. It's a very old shell.

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