How to print a debug log

Question

I d like to debug some PHP code  but I guess printing a log to screen or file is fine for me     How should I print a log in PHP code   The usual print printf seems to go to HTML output not the console   I have Apache server executing the PHP code

User · Answer

You can use error log to send to your servers error log file  or an optional other file if you d like

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error log print r  variable  TRUE       might be useful

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If you don t want to integrate a framework like Zend  then you can use the trigger error method to log to the php error log

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Are you debugging on console  There are various options for debugging PHP   The most common function used for quick  amp  dirty  debugging is var dump   That being said and out of the way  although var dump is awesome and a lot of people do everything with just that  there are other tools and techniques that can spice it up a bit    Things to help out if debugging in a webpage  wrap   lt pre gt   lt  pre gt  tags around your dump statement to give you proper formatting on arrays and objects   Ie    lt div gt  some html code             lt a href   lt  php  tpl- gt link   gt   gt some link to test lt  a gt   lt  div gt         dump  tpl like this        lt pre gt  lt  php var dump  tpl     gt  lt  pre gt      And  last but not least make sure if debugging your error handling is set to display errors   Adding this at the top of your script may be needed if you cannot access server configuration to do so    error reporting E ALL   ini set  display errors    1      Good luck

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You need to change your frame of mind  You are writing PHP  not whatever else it is that you are used to write  Debugging in PHP is not done in a console environment   In PHP  you have 3 categories of debugging solutions    Output to a webpage  see dBug library for a nicer view of things   Write to a log file In session debugging with xDebug   Learn to use those instead of trying to make PHP behave like whatever other language you are used to

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This a great tool  for debugging  amp  logging php  PHp Debugger  amp  Logger  It works right out of the box with just 3 lines of code  It can send messages to the js console for ajax debugging and can replace the error handler  It also dumps information about variables like var dump   and print r    but in a more readable format  Very nice tool

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I have used many of these  but since I usually need to debug when developing  and since I develop on localhost  I have followed the advice of others and now write to the browser s JavaScript debug console  see http   www codeforest net debugging-php-in-browsers-javascript-console    That means that I can look at the web page which my PHP is generating in my browser  amp  press F12 to quickly show hide any debug trace   Since I am constantly looking at the developer tools for debugger  CSS layout  etc  it makes sense to look at my PHP loggon there   If anyone does decide to us that code  I made one minor change  After    function debug  name   var   null   type   LOG       I added   name    PHP       name   This is because my server side PHP generates HTML conatining JavaScript  amp  I find it useful to distinguish between output from PHP  amp  JS    Note  I am currently updating this to allow me to switch on  amp  off different output types  from PHP  from JS  and database access

User · Answer

You can use    lt  php       AddLog  anypage php   reason  ERR ERROR       gt    or if you want to print that statement in an log you can use  AddLog  anypage php   string     string ERR DEBUG LOW

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A lesser known trick is that mod php maps stderr to the Apache log  And  there is a stream for that  so file put contents  php   stderr   print r  foo  TRUE   will nicely dump the value of  foo into the Apache error log

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I use cakephp so I use    this- gt log YOUR STRING GOES HERE   debug

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Simply way  is trigger error    trigger error  My error      but you can t put arrays or Objects therefore use   var dump

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You can use    lt  php echo   lt script gt console log  debug log   lt  script gt      gt

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You can use the php curl module to make calls to http   liveoutput com   This works great in an secure  corporate environment where certain restrictions in the php ini exists that restrict usage of file put contents

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You can also write to a file like this    logFilePath       logs debug text   ob start        if you want to concatenate  if  file exists  logFilePath         include  logFilePath        for timestamp  currentTime   date DATE RSS       echo log statement s  here echo   n n currentTime -  log statement here      logFile   fopen  logFilePath   w    fwrite  logFile  ob get contents     fclose  logFile   ob end flush      Make sure the proper permissions are set so php can access and write to the file  775

User · Answer

If you are on Linux   file put contents  your log file    your content      or  error log   your content   3   your log file      and then in console  tail -f your log file   This will show continuously the last line put in the file

[php] How to print a debug log?

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