putenv

(PHP 4, PHP 5)

putenv — 環境変数の値を設定する

説明

bool putenv ( string setting )

サーバーの環境変数に setting を追加します。この環境変数は、カレントのリクエストを実行している間のみ存在します。リクエスト終了時、環境変数は元の状態に戻されます。

ある種の環境変数が変更されることは潜在的なセキュリティリスクとなる可能性があります。safe_mode_allowed_env_vars ディレクティブには接頭辞のカンマ区切りのリストが含まれます。セーフモードでは、ユーザはこのディレクティブで指定された接頭辞で始まる名前を有する環境変数のみを変更可能となります。デフォルトでは、ユーザはPHP_ で始まる環境変数 (例えばPHP_FOO=BAR)のみを変更可能です。注意:このディレクティブが空の場合、PHPはユーザに全ての環境変数を修正できる許可を与えてしまいます!

safe_mode_protected_env_vars ディレクティブには、カンマ区切りの環境変数のリストが含まれます。ユーザは、この環境変数をputenv()により変更することができません。これらの変数は、safe_mode_allowed_env_varsが変更することを許可している場合でも保護されます。

警告

これらのディレクティブは、セーフモードが有効な場合にのみ効果があります!

例 1741. 環境変数の設定


<?php

putenv("UNIQID=$uniqid");

?>

getenv()も参照ください。

add a note User Contributed Notes
putenv

povaddict
05-Jun-2006 09:18


av01 at bugfix dot cc:



"putenv('MYVAR='); // unset, otherwise this will pass when run the next time"

it won't pass when run next time, "At the end of the request the environment is restored to its original state."

av01 at bugfix dot cc
03-Oct-2005 11:32


Please be aware, that using putenv() does NOT effect the superglobal $_ENV[] variable. If you want to, set it seperately



<?php

  putenv('MYVAR=hello');

  assert(getenv('MYVAR') == 'hello'); // passes 

  assert($_ENV['MYVAR'] == 'hello'); // fails!

  putenv('MYVAR='); // unset, otherwise this will pass when run the next time

?>

EricZ <ezsomething at notthere dot com>
22-Sep-2005 05:29


I posted some code to help load this file, but it got pruned 

out by the folks monitoring php.net.  Anyway, the format can 

be loaded from third column of '/usr/share/zoneinfo/zone.tab',

available on every Linux platform I've logged into thus far.

For NYC, it looks like this: "America/New_York". There are 

also generic CST/PST but then you have to be careful when 

daylight savings switches.

EricZ <ezsomethign at notthere dot com>
22-Sep-2005 05:02


Okay, so here's the format that TZ is looking for 

"America/New_York".  You can get all of the timezones 

from a single file on most unix systems.  This code works

on all Linux systems that I have seen (various redhat/deb) 

where you can find this file...  And now you have a nice,

one level nested timezone list by country.



<?php 

     // -- first part, gather all of the zone data

      $zoneSource = '/usr/share/zoneinfo/zone.tab';

      $zoneHandle = fopen($zoneSource, "r");

      if (!$zoneHandle) return NULL;                  //bad file, abort now

      while (!feof($zoneHandle)) {

        $zoneLine = ltrim(fgets($zoneHandle, 4096));

        if ($zoneLine[0]=='#')  continue;           //skip comments

         //Columns...

         // 1.  ISO 3166 2-character country code.

         // 2.  Latitude and longitude of the zone's principal location

         // 3.  Zone name used in value of TZ environment variable.

         // 4.  Comments; present if and only if country has multiple rows.

        $zoneParts = explode("\t",$zoneLine);       //grab parts

        if (count($zoneParts) < 3) continue;       //erroneous line!

        $nameParts = explode('/', $zoneParts[2], 2);   //grab country/name

        $zoneKey = $nameParts[0];                   //country or area



        $insertArray = &$zoneNames;                 //where to insert?

        if (count($nameParts) > 1) {                //area/populous

          if (!isset($zoneNames[$zoneKey]))         //not set before

            $zoneNames[$zoneKey] = array();

          $insertArray = &$zoneNames[$zoneKey];     //grab sub (country)

          $zoneKey = trim($nameParts[1]);           //grab correct key

        }

        $zoneKey = preg_replace('/[_]/',' ', $zoneKey);

        $insertArray[$zoneKey] = trim($zoneParts[2]); //actually set data

      }                                             //end while not eof

      fclose($zoneHandle);

?>

Eric Z <ezsomething at notthere dot com>
22-Sep-2005 04:58


Hello, actually in answer to your question, I use putenv 

regularly to control the timezone info.  Here's the code that 

sets both the local environment and SQL to the right 

timezone.  I also use it when running a cvs client through the 

web.  I will post what format it's looking for next.



<?php

      //this isn't the most graceful approach, but if it's set, set the tz

      if (isset($_SESSION[BEE_PROFILE_TZOFFSET])) {

        putenv('TZ='.$_SESSION[BEE_PROFILE_TZOFFSET]);

        //format the timezone for SQL

        $timeZone = preg_replace('/([+-]\d{2})(\d{2})/',

                                              '\'\1:\2\'', date('O'));

        mysql_query('SET time_zone='.$timeZone);

      }

?>

otie at ev1 dot net
27-Mar-2005 01:02


trying to change timezones using putenv:

In my case (php 4.2.2) (redhat 2.4.21-1.1931.2.274) TZ does not show up in either the PHP or Linux environment. I'm not sure what the format for TZ is. I tried TZ=EST5EDT. It seemed to work. When I started a session with another browser, it worked there too. Even though I didn't change the environment there.... Hmmm.

When I ran the test without the putenv... the date() function would sometimes show CST (my zone), sometimes EST. Every time I reloaded the page, the time would change zones. All times from a database - not time() time.

Restoring my TZ=CST didn't help. The times would still switch back and forth.

I finally restarted Apache. That worked. The times are now stable.

I think the only solution is subtracting (or adding) the appropriate time difference from the time stamp.



I wonder what the time functions are looking at.



O.

Iavor
08-Feb-2005 07:06


Compare to apache_setenv() and apache_getenv().



I had a case setting an env var in VirtualHost which I tried to change with putenv() - but did not work.



apache_setenv() worked.

cap at capsi dot com
28-Mar-2003 03:18


I've been using putenv with PHP 4.3.1 and Apache 2.0.44, but it does not seem to restore variables correctly. I'm getting +0100 and -0800 entries all across my Apache logs. Manually adding a putenv in page footers to restore the original value seems to fix things, but I still wish I could set the time zone for a specific request only.



I'm not sure whether using putenv affects all threads within the process, that could be another problem.

verkoop at it-design dot com
08-Mar-2001 08:19


for those who have problems with the putenv ('TZ=Europe/Amsterdam').


I found that there is a solution/work-a-round. It will work, but only if you add  mktime(0,0,0,1,1,1970) on the next line. So:





putenv ('TZ=Europe/Amsterdam');


mktime(0,0,0,1,1,1970)


echo date("H:i:s");

johnhill at webtendon dot com
11-Feb-2001 06:46


Here is an example of using putenv to change the timezone for the current script.  You would have to add a putenv() call to each page in which you wanted to change the timezone.  This was posted here about a year ago...I forgot the author's name.  He mentioned to "see the zoneinfo directory-tree on your System for a list". This is usually /usr/share/zoneinfo or /usr/lib/zoneinfo.  It works in PHP3, not sure about PHP4.





  //Set the Timezone


print("server timezone is: " . getenv('TZ') . "<br>\n");


  print("server time is: " . date("H:i:s") . "<br><br>\n");


  print("changing server time zone to US/Pacific....<br><br>\n");


  putenv("TZ=US/Pacific");


  print("new server time is: " . date("H:i:s") . "<br>\n");


  print("new server timezone for this script is: " . getenv('TZ'));





some Unix servers may use a different format for TZ.  Example: putenv("TZ=PST8EDT");

david dot boyce at messagingdirect dot comnospam
14-Sep-2000 02:23


Environment variables are part of the underlying operating system's


way of doing things, and are used to pass information between a parent


process and its child, as well as to affect the way some internal


functions behave.  They should not be regarded as ordinary PHP


variables.





A primary purpose of setting environment variables in a PHP script is


so that they are available to processes invoked by that script using


e.g. the system() function, and it's unlikely that they would need to


be changed for other reasons.





For example, if a particular system command required a special value


of the environment variable LD_LIBRARY_PATH to execute successfully,


then the following code might be used on a *NIX system:





 $saved = getenv("LD_LIBRARY_PATH");        // save old value


 $newld = "/extra/library/dir:/another/path/to/lib";  // extra paths to add


 if ($saved) { $newld .= ":$saved"; }           // append old paths if any


 putenv("LD_LIBRARY_PATH=$newld");        // set new value


 system("mycommand -with args");        // do system command; 


                        // mycommand is loaded using


                        // libs in the new path list


 putenv("LD_LIBRARY_PATH=$saved");        // restore old value





It will usually be appropriate to restore the old value after use;


LD_LIBRARY_PATH is a particularly good example of a variable which it


is important to restore immediately, as it is used by internal


functions.





If php.ini configuration allows, the values of environment variables


are made available as PHP global variables on entry to a script, but


these global variables are merely copies and do not track the actual


environment variables once the script is entered.  Changing


$REMOTE_ADDR (or even $HTTP_ENV_VARS["REMOTE_ADDR"]) should not be


expected to affect the actual environment variable; this is why


putenv() is needed.





Finally, do not rely on environment variables maintaining the same


value from one script invocation to the next, especially if you have


used putenv().  The result depends on many factors, such as CGI vs


apache module, and the exact way in which the environment is


manipulated before entering the script.

add a note

restore_include_path

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Last updated: Mon, 05 Feb 2007