deleting a line from a text file

[Anon]

hi,
i was wondering, how would i delete a line from a text file.

say if the line was in the format:

[e-mail] username

with the variables as

$alias@$domain $username

How could i delete a particular email address from the file email.txt?

Any help is appreciated

Thanks!
Khilan Gudka

[Anon]

If you know what the mail & user name is- you can use str_replace() to delete the line - thats the easy way but it means reading the whole file and then writing it back again - how big is the text file?

[Anon]

hi,

at the moment, the file isnt very big maybe 1K. BUT im assuming that in the future its gonna get very big. So is there another way to approach it? By the way, i would know the email address as it is also stored in a mysql database (however this is just for records and nothing to do with what i am trying to do).

Any help would really be appreciated.

Thanks,
Khilan Gudka

[Anon]

Hi,

maybe you can do it by calling some shell commands with exec.

Example:

The text file is named: aliases

you could execute a "mv aliases aliases.old"
and then execute a grep or awk command with output to aliases.

T.

[Anon]

i dont understand,

All i want to do is store information in one file and be able to delete from it.

thanks,

khilan

[Anon]

hey - check 0ut this tutorial http://bythailand.com/saif/managedb.htm

potsed today by a phpBuilder forum user - its quite good and covers most of the stuff you are looking for.

[Anon]

thanks for that, i'll look into it! one last question tho, if i have the found item into an array, how would i then delete it.

delete($found); ??? or if i would use the str_replace would it be... str_replace("$found", "", "$found"); ???

please can u help,

Thanks!

Khilan

[Anon]

$fd = fopen("textfile.txt", "r");
while (!feof($fd)) {
$buffer = fgets($fd, 32000);
echo $buffer;
}
fclose($fd);

//now $buffer contains the whole text file//
//remove the bits you want with str_replace or regex//

$str_replace("[e-mail]","",$buffer);

//rewrite the file//
$fd = fopen("textfile.txt", "w");
$done = fputs($fd,$buffer);
fclose($fd);

This reads the whole file into memory - which is fine for files less than 32k ish but gets slower for larger files.

You can read through the file line by line until you get the bit you want but that is a whole different kettle of fish.

regards,

Simon Wheeler.

[Anon]

hi simon,

i really appreciate the help that you have given me. :o). I still am running into problems. i inserted in the code and added the str_replace as told and put in the right string, however, when i press delete, all the records in the file show up on the screen, i spose thats what echo $buffer is for .

however, then it just deletes the WHOLE file not one record.

Any ideas?

Cheers, i would appreciate any help. Also, what about if the file was more than 32k, is there anything u could recommend i do to prevent future problems?

Thanks,

Khilan

[Anon]

Hi folks,

I think there are possibly two errors in this script.

(1) $buffer = fgets($fd, 32000); should be
replaced with
$buffer .= fgets($fd, 32000);
add a dot, because otherwise $buffer is overwritten every execution of the loop.
The effect is that the file email.txt will be more or less overwritten with empty content.

(2) $str_replace("[e-mail]","",$buffer);

I think, the goal was to do
$str_replace("[e-mail] username","",$buffer);
Maybe you want to use ereg_replace() if there's a chance that there is more than one space ore a tab between 'add' and 'username'?

Using ereg_replace() can increase execution time a lot.

Another approach (I couldn't test it):

<?PHP

function checkMail((&$item,$key) {
if (strstr($item,"[e-mail] username")) {
$item="";
}
}

$lineArr=file("email.txt");
array_walk($lineArr,'checkMail');

$fd=fopen("email.txt","w");
fputs($fd,implode("",$lineArr));
// maybe you need this, but I don't think so
//fputs($fd,implode("\n",$lineArr));
fclose($fd);

the file() function reads a file of size 1,5MB in about 2 sec. into an array on a P233MMX. I don't know how fast array_walk is ... just test it.

Greetings,
Thomas 🙂

[Anon]

Sorry Khilan - Thomas is right - I missed out the dot! - small dot -big difference.

I echoed the $buffer just to show you what was going on - you do not need to.

[Anon]

The script with some repairs.
$fd = fopen("textfile.txt", "r");
while (!feof($fd)) {
$buffer .= fgets($fd, 32000);
//echo $buffer;
}
fclose($fd);

$newbuffer = str_replace("[e-mail]\n","",$buffer);

$fd = fopen("textfile.txt", "w");
$done = fputs($fd,$newbuffer);
fclose($fd)