bash replace string with floating variable

Question

Im trying to replace a number in a file with a calculated floating variable in a bash file. So im trying to replace 1.1111 with the value of "km" and save it in the mesh.in file. I keep getting an error on the sed line, I think there may be an issue with the floating variable. Echo "$km" does work so i know that the km is not the issue

#!/bin/bash
read -p "Angle in degrees : " n1
read -p "bcsa : " n2
cd viv_example_se2d
sed s/^bcsa.\*/"bcsa $n2"/ runfile.viv >temp
mv -f temp runfile.viv
cd ../
for i in $(seq 2 0.5 12)
do
    if  [ ! -d U*_$i ];then
        mkdir U*_$i
    fi
    printf -v "km" "%.4f\n" $(echo | bc | awk "BEGIN {print 4*3.14159265359*3.14159265359/($i*$i)}")
    echo "$km"
    cd viv_example_se2d
    sed s/1.1111/$km/g mesh_master.in > temp$i 

    mv -f temp$i mesh.in
    cd ../
    echo $home/lustre/projects/p057_swin/ogoldman/Ellipse_$n1/U*_$i | xargs -n 1 cp viv_example_se2d/*
done;

That `echo | bc |` bit of that command is doing absolutely nothing and can be dropped. — Etan Reisner, Apr 28 '15 at 14:58
And what is the value of `$km` exactly? Oh! Drop the `\n` from your `printf` format. You don't want the value of `$km` to contain a newline. — Etan Reisner, Apr 28 '15 at 15:45
Show sample input and expected output as we can't tell from a non-working script what it is you are trying to do but we CAN tell it's the wrong way to do it (since it's the wrong way to do anything). — Ed Morton, Apr 28 '15 at 16:32
The problem is the newline in the value of `$km`. That being said EdMorton is exactly correct in that this script is (as I indicated in my comment and my answer) a big mess. — Etan Reisner, Apr 28 '15 at 17:49
inputs would be degrees anything between 0 and 90 and bcsa would be something like 0.52360 or 0.72305 its a function of the degrees that varies and is calculated elsewhere — Osher Goldman, Apr 29 '15 at 00:09

Etan Reisner · Answer 1 · 2015-04-28T17:52:26.060

1

The problem is the newline in the value of $km. It is confusing sed.

That being said this script is also a bit of a mess.

You should quote your variables when you use them to protect against problems with whitespace and glob characters in the values.

You don't need xargs to cp multiple files that you can expand via a glob. cp will happily take multiple files to copy directly. (Oh, or is that copying multiple files to directories produced via that glob?)

You have a useless echo | bc | bit near the awk command.

Using full/relative paths in sed/etc. is better than cding around generally.

edited Apr 28 '15 at 17:52

answered Apr 28 '15 at 15:00

Etan Reisner

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Didnt mean to have the `-i ` and `| bc - l `. I was playing around trying a few different things and couldnt fix it. Script has been editted. Also dont worry about the `$..../U*_$i` it had a long path so i just removed the beginning which isnt important – Osher Goldman Apr 28 '15 at 15:21
1

You need to show us **exactly** the code you are working with and **exactly** the problem you are having or we can't help you correctly. – Etan Reisner Apr 28 '15 at 15:24

bash replace string with floating variable

1 Answers1