making lines in a file shorter

[peter_brickles]

I have a list of longitudes in the following format





53.961224
53.964072
53.96492
53.96392
53.96347




in a text file but I need to make then just four digits after the decimal point




53.9612
53.9640
53.9649
53.9639
53.9634



does any one know of a one liner sed perl awk ? To accomplish this or any other ways without going through the 10k or so lines by hand ?


Any help would be gratefully appreciated




Pete

[Vaphell]

$ grep -Eo '[0-9]+[.][0-9]{4}' test.data
53.9612
53.9640
53.9649
53.9639
53.9634
$ sed -r 's/([0-9]+[.][0-9]{4}).*/\1/' test.data
53.9612
53.9640
53.9649
53.9639
53.9634
$ awk '{ printf ( "%.4f\n", $1 ); }' test.data
53.9612
53.9641
53.9649
53.9639
53.9635

note that awk will properly round the number instead of just dropping digits.

[steeldriver]

... to add,



perl -ne 'printf("%.4f\n", $_)' test.data




while read val; do printf '%.4f\n' "$val"; done < test.data


The perl one has the advantage of being able to modify the file in-place (with the -i option)