Read and replace text in a file, save as .m

I have a .prm file i am trying to manipulate the values of within a script I created. I am able to find the specific line the text i am trying to change using

st = fopen('changes.txt','r') % i changed the file type to a .txt file and placed it in the same location
fgetl(st) %have to use this command 7 times before I find the right line.

But that is as far as I've gotten that seems to be right. the file is of the format

    command                 argument

where I am attempting to change the numerical value used in argument.

Have attempted using a number of functions to load the data and fopen was the only one that seemed to get anywhere

Thanks!

Answer 1

[Walter Roberson]

S = fileread('changes.txt');

newS = regexprep(S, 'command.*$', 'command NEWVALUE', 'dotexceptnewline', 'lineanchors');

fid = fopen('new_changes.txt', 'wt');
fwrite(fid, newS);
fclose(fid);

[Charles Cummings]

Is it possible to loop through the newvalue?

S = fileread('changes.txt');
newvalue=0
for newvalue<10000
    newvalue=newvalue+500

newS = regexprep(S, 'command.*$', 'newvalue', 'dotexceptnewline', 'lineanchors');

fid = fopen('new_changes.txt', 'wt');
fwrite(fid, newS);
fclose(fid);

end

Obviously wouldnt be that simple.