CODEWITHSUNDEEP
php
P K
P K

Reputation: 10210

PHP: how to write in between content of existing file?

How to write in between content of existing file?

I tried to use fseek() to seek a new position and write the new content, but it replaces old content to the new string after seek position.

My aim is to put new contents after 5 characters of existing file.

Old content: AAAAABBBBB, desired content: AAAAAnewcontentBBBBB

$file_handler = fopen('putty.log','w');
$new_content = 'this is new content';

fseek($file_handler,5);

echo ftell($file_handler); //5
fwrite($file_handler,$new_content);

old content replaced with NULLNULLNULLNULLNULLthis is new content

Upvotes: 1

Views: 624

Answers (4)

Yaniro
Yaniro

Reputation: 1587

Writing in the middle of the file won't cause it to stretch and push the content forward (like when inserting content in a text editor) but rather to overwrite the content at the position you start writing. What you need to do is:

  1. read the first part of the old data until the point where you need to write the new content & write that part to a temporary file.
  2. write the new content to the temporary file (the stuff you wish to add).
  3. read the rest of the content from the old file & write it to the temporary file.
  4. delete the old file.
  5. rename the temporary file to the name of the old file.

Example:

$original_file_name = '/tmp/putty.log';
$temp_file_name = '/tmp/putty.tmp';
$temp_file = fopen( $temp_file_name, 'w' );
$file_handler = fopen( $original_file_name, 'r' );
$old_data_size = 5;
fwrite( $temp_file, fread( $file_handler, $old_data_size ) );
$new_content = 'this is new content';
fwrite( $temp_file, $new_content, strlen( $new_content ) );
fwrite( $temp_file, fread( $file_handler, filesize( $original_file_name ) - $old_data_size ) );
fclose( $file_handler );
fclose( $temp_file );
unlink( $original_file_name );
rename( $temp_file_name, $original_file_name );

Make sure that putty.log has read/write permissions for the user used by your webserver (apache/lighttpd etc.) process or that it's accessible for everyone (not recommended).

Upvotes: 1

Alireza
Alireza

Reputation: 6848

if you're using fseek() to write data to a file, remember to open the file in "r+" mode, example:

$fp=fopen($filename,"r+");

Upvotes: 1

Riccardo Galli
Riccardo Galli

Reputation: 12925

You can't do it that way.

You can only truncate the content with ftruncate and write later the old content

A not so clean example

<?php

$file_handler = fopen('putty.log','rb+');
$new_content = 'this is new content';

fseek($file_handler,5);

$restOfContent = fread($file_handler,filesize('putty.log')-5);

ftruncate($file_handler,5);
fseek($file_handler,5);

echo ftell($file_handler); //5
fwrite($file_handler,$new_content);

fwrite($file_handler,$restOfContent);

fclose($file_handler)

Upvotes: 1

Svisstack
Svisstack

Reputation: 16616

  1. Load contents to variable using file_get_contents().
  2. Do this on your buffer.
  3. Save your contents to this file using file_put_contents();

Upvotes: 1

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