I'm trying to do floating point arithmetic in a shell script. I learned that awk can do it on the command line, but the way it works there does not seem to carry over to a shell script. When I type awk below, it turns gray, as if to say that bash doesn't recognize it. When I run it, $ ./script a 30 40, I get 0. What am I doing wrong?
#!/bin/bash if [ $1 = a ] then echo | awk '{print $2 + $3}' 
#!/bin/bash if [ $1 = a ] then echo "$@" | awk '{print $2 + $3}' fi The $2 and $3 are not related to $1 of the script but are in awk.
Consider this if you always trust the args being passed to it:
$ cat script awk 'BEGIN{ print '"$*"' }' $ ./script 30 + 40 70 $ ./script 30 \* 40 1200 $ ./script 30 / 40 0.75 Note the need to escape * as it's a globbing char, otherwise quote the args, e.g.:
$ ./script '30 * 40' 1200 Also, with this approach you're not limited to simple arithmetic expressions:
$ ./script 'log(10)' 2.30259 $ ./script 'exp(10)' 22026.5 $ ./script '10^2 - sqrt(9)' 97 
echodo in general? So what doesechodo in your script?