Shell Programming and Scripting

Hello I am trying to make an awk script that always replaces the same characters in a file, with white space in between. Can anyone write a script that prompts for the 3 numbers and then replaces them in the file?
eg.
enter a b c:
'it then puts a b c in the file.

The file format is always

npts 40 40 40 # num.grid points in xyz
gridfld rec_flex.maps.fld # grid_data_file
spacing 0.375 # spacing(A)
receptor_types A C HD N OA # receptor atom types
ligand_types C HD N OA # ligand atom types
receptor rec_flex.pdbqt # macromolecule
gridcenter 9.9 -16.8 -7.3 # xyz-coordinates or auto
smooth 0.5 # store minimum energy w/in rad(A)
map rec_flex.C.map # atom-specific affinity map
map rec_flex.HD.map # atom-specific affinity map
map rec_flex.N.map # atom-specific affinity map
map rec_flex.OA.map # atom-specific affinity map
elecmap rec_flex.e.map # electrostatic potential map
dsolvmap rec_flex.d.map # desolvation potential map
dielectric -0.1465 # <0, AD4 distance-dep.diel;>0, constant

it is these 3 numbers that need to be changed:
gridcenter 9.9 -16.8 -7.3
the resulting file is ref.gpf

With awk you can do something like:

Code:

awk 'BEGIN{
  printf "Enter the values separated by a space : "
  getline var < "-"
  split(var,a)
}
/gridcenter/{$2=a[1]; $3=a[2]; $4=a[3]}
{print}' file

Regards

Thanks, this works great but I need to update the original rather than to std output.
Thank you.

Redirect the output of the awk command to a temporary file and replace the original file with it:

Code:

awk '...' file > tempfile
mv tempfile file

These are basic shell commands, have a read of one of the tutorials here:

https://www.unix.com/answers-frequent...tutorials.html

Regards

yes that was the 1st thing I tried but the script failed. I will pursue this.
gav

Hi when I use > or | the script fails. Why's this?
The link didn't.
gs

May be you don't have a permission to create a file in that directory.
Basically the elimentary nature of > should write to a file as franklin has given its fine.
You can also "touch" a file and then append the out put to that file.
You will come to know while "touch" when u can create the files in that dir.