Writing to specific lines of a program

[Brian3]

Hi,

I have a SAS program. Using the file mod and put statements I can append lines to the end of this program. But say I want to write "hello" to line 1 or line 30 or any specific line of the code. How would I go about doing that?

Thanks.

[Tom · Accepted solution]

---

@Brian3 wrote:

Hi,

I have a SAS program. Using the file mod and put statements I can append lines to the end of this program. But say I want to write "hello" to line 1 or line 30 or any specific line of the code. How would I go about doing that?

Thanks.

---

Your description is a little muddled.  Are you talking about running a data step to modify an existing text file?  What does this file contain? How is it structured?

To modify a file make a COPY of the file.

data _null_;
  infile 'original file';
  file 'new file';
  input;
  if _n_=1 then put 'hello';
 else put _infile_;
run;

[Brian3]

Thanks for replying,

It's any program (say it contains a list of marco variable definitons). Its a .sas file if that's what you mean by text.

Yes, what I have at the moment is

data _null_;

file "original" mod;

put "hello";

run;

but I want to be able to write the "hello" at any specific line of the code.

[Kurt_Bremser]

The option MOD in a FILE statement causes new lines to be appended. @Tom has provided the solution, as you cannot open a file simultaneously for input and output. 

[RichardDeVen]

You can use an ordered hash to maintain the lines read in from a file.  Modify the hash and write the information back out to the same file.

Example:

data _null_;
  %textfile_to_hash(settings,lines);

  rc = lines.remove(key: 1);
  lines.replace(key: 5, data: 'parameter5 = 555;');
  lines.replace(key:10, data: 'parameter10 = 4096');
  lines.replace(key:12, data: 'parameter12 = 121212');

  %hash_to_textfile(lines,settings);
run;

Full program with macros

Spoiler

* Create a sample text file;
filename settings 'parameters.sas';

data _null_;
  file settings;
  do row = 1 to 10;
    put 'parameter' row ' = ' row ';';
  end;
run;

data _null_;
  infile settings;
  input; put _infile_;
run;

%macro textfile_to_hash(fileref,hash,log=0);
  length index 8 line $256;

  declare hash &hash.(ordered:'A');
  &hash..defineKey('index');
  &hash..defineData('line');
  &hash..defineDone();
  call missing (index, line);

  fid = fopen ("&fileref");
  msg = sysmsg();

  if fid ne 0 then do;
    do index = 1 by 1 while (fread(fid)=0);
      if fget(fid,line,256)=0 then 
        &hash..add(key:index, data:line);

      %if &log %then
        %str(put index 2. ': ' line;  * log the file data;);
    end;
    fid = fclose(fid);
  end;
  else
    put msg;
%mend;

%macro hash_to_textfile(hash,fileref);
  fid = fopen("&fileref","O");
  msg = sysmsg();

  if fid ne 0 then do;
    declare hiter iter("&hash");
    do while (iter.next()=0);
      rc1 = fput(fid,line);
      msg = sysmsg();
      if rc1 = 0 then rc2 = fwrite(fid);
      if rc1 or rc2 then putlog msg;
    end;
  end;
%mend;

data _null_;
  %textfile_to_hash(settings,lines);

  rc = lines.remove(key: 1);
  lines.replace(key: 5, data: 'parameter5 = 555;');
  lines.replace(key:10, data: 'parameter10 = 4096');
  lines.replace(key:12, data: 'parameter12 = 121212');

  %hash_to_textfile(lines,settings);
run;

data _null_;
  infile settings;
  input; put _infile_;
run;