Delete a some strings from text file

Question

There is text file about 3 GB. I need to delete a some strings from this, but I'm not sure that my method is good. I did next steps: - read echo string from the doc - find needed strings to delete - get 2 massive: strings to save and strings to delete

What is must next steps? Yeah, this task looks easy for small docs, but there are more issues with giant file.

Show us what you've tried that isn't working. For a file that size I would go through it line by line and put what you want to save into a temporary file. You probably don't want to try bringing the entire file into memory. — Dave, May 04 '18 at 17:23
I wouldn't use PHP for that. You can do this very efficiently with sed under linux - see: https://stackoverflow.com/questions/5410757/delete-lines-in-a-text-file-that-contain-a-specific-string — maio290, May 04 '18 at 17:38
@Dave, you are right. My last step was saving of needed strings in array. I limited by 50 strings for testing, because I don't know what expect from 1000+ in memory and look for ways to make more optimize. — Paul K., May 06 '18 at 22:05

Jason Smith · Answer 1 · 2018-05-04T19:03:32.710

if( $fh = fopen("file.txt", "r") ){ 
        $left='';

        while (!feof($fh)) {// read the file
        $temp = fread($fh);  
        $fgetslines = explode("\n",$temp);
        $fgetslines[0]=$left.$fgetslines[0];

             if(!feof($fh) )$left = array_pop($lines);           
             foreach($fgetslines as $k => $line){
                   //This is where you can build your check for the strings you want to remove 
                   //if statement or switch, which ever makes sence with your current logic.
                   //After excluding your strings from the temp file 
                   //overwrite your original file with the temp file of proper strings that you want.
              }
        }
}
fclose($fh);

I think this is what your looking for.

I didn't know before about fread. But I'm thinking that opations with 3 GB file as array is bad idea. Also, looks like to use fread and while is not correct. This script also will report about $lines doesn't exist. My main question is how to better work with 3 GB file and don't kill software. — Paul K., May 06 '18 at 22:33

Delete a some strings from text file

1 Answers1