Shantanu's Blog

// contents of showcode.php file

?php
$source = $file;
highlight_file( $source [ $return = false ] );

?>

It is possible that "return=false" may not work on older browsers and / or Linux OS. We can make any php file printable by passing the file name as variable in the URL. for e.g.

http://my_web_site.com/showcode.php?file=toprint.php

Labels: php tips, usability

There are times when you see the following PHP error in the error log.

[Mon Aug 02 14:28:11 2010] [error] PHP Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 292995097 bytes) in /var/www/html/text.inc on line 25, referer: https://yahoo.com/Compose.php?con_id=cand74035

The usual fix for this problem is as follows. At the top of the compose.php page use the following statement.

ini_set("memory_limit","200M");

This will increase the memory allocation for the current page only.

Labels: php tips

There are times when you need to check the latest entries in the apache error log.
Here is the easy way to do so.

Cron entry:
# extract of apache error log
# updated every 5 minutes and posted to http://yourSite.com/shantanu/index.txt
*/5 * * * * sh /home/develop/apache.sh >> /home/develop/apache_succ.txt 2>> /home/develop/apache_err.txt

Shell script:

# cat /home/develop/apache.sh
#!/bin/sh

mytemp='/home/develop/mytemp.txt'
mypath='/home/develop/index.txt'
> $mypath
> $mytemp

for file in `find /var/log/httpd/ -name "*log"`
do
tail -100 $file | grep "`date +%h\ %d`" >> $mytemp
done

sed -i '/^$/d' $mytemp
grep -v 'favicon' $mytemp > $mypath
mv $mypath /var/www/html/shantanu/

Labels: php tips, shell script

There are times when you see the following error in the apache error log.

[Sun Aug 08 14:06:12 2010] [error] [client 199.199.199.199] PHP Strict Standards: date() [function.date]: It is not safe to rely on the system's timezone settings. Please use the date.timezone setting, the TZ environment variable or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/New_York' for 'EDT/-4.0/DST' instead in /var/www/html/global_fun.inc on line 524, referer: https://yahoo.com/edit.php?acc=deliver&addr=543

This is because of timezone mismatch.

You can export the time zone variable as shown below.
export TZ="America/New_York"

Or add it to the php.ini file.

[Date]
; Defines the default timezone used by the date functions
date.timezone = America/New_York

Or else, set the timezone in the code itself.

date_default_timezone_set('America/New_York');
echo date('D,F j, Y, h:i:s A');
?>


You can check the current time in the following file.

# cat /etc/sysconfig/clock
ZONE="America/New_York"
UTC=true
ARC=false

The following file shows that we are not sure about the current localtime. It is probably taking the time from system clock.

# ls -l /etc/localtime
-rw-r--r-- 1 root root 1267 Mar 5 2008 /etc/localtime

The localtime file needs to be linked to the correct time zone.
ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime

All the above examples use America (New York) timezone has default one. You will have to change it if you need a different zone.

Labels: linux tips, php tips

If you use exec to execute the UNIX command or shell script then you do not get the exit status.
passthru command will allow you to save and use the exit code.

$synarray='myfile';
passthru("gunzip ".$synarray.".sql.gz > /dev/null 2>&1", $returnvalue);


if ($returnvalue != 0){
echo "no success";
}else{
echo "success";
}

Labels: php tips, shell script

The logger command can be used anywhere in the script or PHP code that will log messages to... guess where? /var/log/messages

mysql_query("show databases") or die(exec('logger "show db query error on line 87 of index.php"'));
_____

mysql_query('update mytest set id = 12 where id = 103;');
$mycount = mysql_affected_rows();
if( "$mycount" == 0) {
exec('logger "update mytest failed for the value 12 the old value 103 was retained at `date`"');
}

Labels: php tips

There is a very easy way to find PHP syntax errors.
If all your .php files are in /var/www/html then you can type the following command.

# find /var/www/html -name '*.php' -exec php -l {} \; | grep -v '^No syntax'

You can save the output to a text file by appending "> tofile.txt" at the end of the above command.
The output will look something like this...

Parse error: syntax error, unexpected '<' in ./reports/extra/rc7bkp2.php on line 265
Errors parsing ./reports/extra/rc7bkp2.php

Parse error: syntax error, unexpected $end in ./reports/extra/rc6bkp.php on line 525
Errors parsing ./reports/extra/rc6bkp.php

Parse error: syntax error, unexpected '}' in ./login/login.php on line 53
Errors parsing ./login/login.php

Parse error: syntax error, unexpected $end in ./commom/bkp/25_nov/Process1.php on line 93
Errors parsing ./commom/bkp/25_nov/Process1.php

_____

If you want to check if a file for e.g. reserve.php has any errors, use the following command....

$ tail -f /var/log/httpd/error_log | grep 'reserve.php'
[Fri Dec 18 16:46:30 2009] [error] [client 59.95.20.15] PHP Notice: Undefined index: ucd in /var/www/html/login.php on line 531, referer: http://111.222.333.444/reserve.php
[Fri Dec 18 16:46:33 2009] [error] [client 117.195.35.82] PHP Notice: A session had already been started - ignoring session_start() in /var/www/html/checkPass.php on line 2, referer: http://666.777.888.999/reserve.php

Labels: php tips

avoid SQL Injection

It can happen anywhere you have a form that the user can fill in and submit.
There is a PHP function to avoid the SQL Injection attack.

$query_ok = "SELECT * FROM users WHERE username = 'mysql_real_escape_string($injection_string)'";

Real escape strings will replace all single quote and double quote character with the escaped string \

$new_user=mysql_real_escape_string($_GET["injection_string"]);

$query_ok = "SELECT * FROM mysql.user WHERE User = '" . "$new_user" ."' limit 1";
echo $query_ok;
$result=mysql_query($query_ok) or die("some errror");

_____


If you need to use SMTP server to send mail, here is a nice writeup for the same.

http://9lessons.blogspot.com/2009/10/send-mail-using-smtp-and-php.html

Labels: php, php tips