Cutting numbers into a specific decimals

You can use sed:

sed -E 's/([0-9]+\.[0-9]{5})[0-9]*/\1/g' file

Add -i option to add file in place.

If you don't mind the integers also being converted to floating point, you could use numfmt:

$ numfmt --field=1- --format=%.5f --invalid=ignore < file
1.00000
            12.23487              0.00000              0.00000
             0.00000              3.03201              0.00000
            -1.37521              0.00000              5.61831
   Ga    O
8.00000 12.00000
Direct
         0.59003             0.50000             0.79426
         0.40998             0.50000             0.20575
         0.90998             0.00000             0.20575
         0.09003             0.00000             0.79426
         0.65889             0.00000             0.31409

Explanation

• --field=1-

  This option tells numfmt which occurrences need to be replaced. 1- in this case means from the first occurrence until the end of the line.

• --format=%.5f

  This option tells numfmt how to format the output numbers. %.5f in this case means format them as floating numbers with 5 decimal digits.

• --invalid=ignore

  This option tells numfmt what to do in case it was not able to format a number. ignore in this case just ignores the problematic input and carries on with next input.

By default, numfmt applies IEEE 754 rounding rules - if you want simple truncation, you can add --round=towards-zero. The complete list of rounding options is up, down, from-zero (default), towards-zero, nearest.

You can view manpage for more details:

• http://manpages.ubuntu.com/manpages/bionic/man1/numfmt.1.html

If you want IEEE 754 rounding but want it to apply strictly to floating point numbers with more than 5 digits after the point, then I'd suggest using perl - it can match regular expressions, like sed, but allows you to apply a sprintf expression to the captured pattern:

perl -pe 's/[+-]?\d*[.]\d{5,}/sprintf "%.5f", $&/ge' file

Like GNU sed, perl can modify the file in-place by adding the -i option.