Replacing a string in a file with another string.

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quiknot
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Replacing a string in a file with another string.

Postby quiknot » Tue Apr 01, 2003 1:10 pm

Hello, I have a quick question.

I need to be able to open a file, search through it until I find a string, and then replace that string with a new one. I am somewhat new to PHP so I thought I could get some help here.

The variables are:
$info_string_old //Find this string in file
$info_string //Replace with this string

The file name is:
file_info


First post, please be nice :D

HighOrbit
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Postby HighOrbit » Wed Apr 02, 2003 6:15 pm

I think you probably need to do several steps to get what you want here.

to open and read a file you need to use fopen() and fread() to push the file contents into a string.

http://www.php.net/manual/en/function.fopen.php
http://www.php.net/manual/en/function.fread.php

Once the contents are in the string, you can use regular expression functions like ereg_replace() or preg_replace() to search through the string for a pattern and replace that pattern with a new one.
http://www.php.net/manual/en/ref.regex.php

if you want to write the new data back to the file, then use fwrite() and then fclose() to finish up.

http://www.php.net/manual/en/function.fwrite.php
http://www.php.net/manual/en/function.fclose.php

The regular expression part is probably going to be the hard piece. Regular expressions can be complicated depending on the level of complexity of the patterns working with.

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Redcircle
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Postby Redcircle » Wed Apr 02, 2003 6:22 pm

str_replace also works nice.

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quantm
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Passwd change

Postby quantm » Wed Apr 09, 2003 6:59 pm

I have wrote a function to replace an user password in passwd file under linux as follows:

function replace_passwd_full($filename,$username,$newpasswd)
{
$separator = ":";
$data=file($filename);
if (!($pipe = fopen($filename, "w"))) {
return false;
}
$size=count($data);
for($line=0;$line<$size;$line++) {
$dataline = $data[$line];
$dataline= preg_replace("/".$username.":(\S+):/i", $username.":".$newpasswd.":\$3", $dataline);
fputs($pipe,$dataline);
}
fclose($pipe);
return true;
}

Hope that helps!! :roll: :wink:


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