PHP: exec command not working; sh: command not found

When using PHP exec command, if you find sh: Command not found , error in your web server logs, you have to export the full path of that command.

Assuming, that command in /opt/local/bin, change the command to

 $cmd ='export PATH=$PATH:/opt/local/bin; myCommand 2>&1';  
 echo exec($cmd,$out);  

To debug PHP exec command, Read this

For example:
For the PHP code:

 $cmd = "gmake";  
 echo exec($cmd,$out);  

There will be no output. In your web server error log, your will have :

 sh: gmake: command not found  

To fix this, we need to export the PATH of the gmake.

Go to your terminal, find where your command is located, In this example:

 $ which gmake  
 /opt/local/bin/gmake  

So, modify you PHP code as following:

 $cmd ='export PATH=$PATH:/opt/local/bin; gmake 2>&1';  
 echo exec($cmd,$out) ;

This will output, on your web page

 gmake: *** No targets specified and no makefile found. Stop.  

PHP: exec command not working; debugging exec command

While using PHP exec command, if it is not working , Follow these to debug

1. Check your web server error_log.
Usually in MAC, for APACHE web server, it is located at /var/log/apache2/
1.1 Case1: the web server does not have permission to read/execute a command/file.
Solution to Case1: Simple, change file permissions.

1.2 Case2: The exec command will throw sh: Command Not found
Solution to Case2: Read this

2. Append 2>&1 to your command to get std errors as well. Read this for more info

PHP: Today, Yesterday, Tomorrow dates

In PHP, we can generate Today, Yesterday, Tomorrow Dates the following way:

 $today = date('Y-m-d');  
 $tomorrow = date('Y-m-d', strtotime('tomorrow'));  
 $yesterday = date('Y-m-d', strtotime('yesterday'));  

MySQL: Make a copy of an existing table in MySQL

We can create a copy of an existing table using the following SQL statements.

 CREATE TABLE booger_copy LIKE testing.booger;  
 INSERT booger_copy SELECT * FROM testing.booger;  

If you want to copy only half of the existing table then, you can use LIMIT keyword in the select Query

Mac: Running 32-bit JVM on Mac OSX using eclipse

I had to use SMILE API on 64-bit Mac OSX machine.
SMILE API provides 32-bit version of their binaries.

I found a way to use 32-bit JVM in Mac OSX 64bit machines using Eclipse.
By default Mac OSX comes with both 32 bit and 64bit JVM installed.
Eclipse uses 64-bit JVM by default.

In order to use the 32-bit JVM, do the following in Eclipse
1. Right Click on your project, goto "Run As", Select "Run Configurations"
2. Select the Arguments tab,
3. Add “-d32″ in VM arguments field.

Using Filezilla to login into Amazon EC2 instance and transfer files

We can login into Amazon EC2 instance using Filezilla FTP client for simple transfers of local files.
Following are the steps:

1. Download and install Filezilla client.
2. Goto Filezilla settings(Windows) or Filezlla preferences (MAC)
3. Click on SFTP, on right side, click on add key file.

4. Select your .pem file. It will prompt you to convert into PPK file.

5. Click ok to close the settings/preferences window.
6. Open site manager, create a new site as show in the image below.
Host: your AMI address
ServerType: SFTP
Logon Tpe: Normal
User: ec2-user
No password required ! Filezilla will read through the keys and find the right key for the user/server pair that you are connecting to.

Using cURLpp software

To use the curlpp, we need to first install.

Download the package at  http://curlpp.org/index.php/download

The simplest way to compile this package is:

  1. `cd' to the directory containing the package's source code and type
     `./configure'

  2. Type `make' to compile the package.

  3. Type `make install' to install, if error occurs do 'sudo make install'

  4. You can remove the program binaries and object files from the
     source code directory by typing `make clean'.

After installing, there are several examples at http://curlpp.org/index.php/examples
cURLpp is a C++ wrapper for libcURL.

libcURL is described as:

a free and easy-to-use client-side URL transfer library, supporting FTP, FTPS, HTTP, HTTPS, GOPHER, TELNET, DICT, FILE and LDAP. libcurl supports HTTPScertificates, HTTP POST, HTTP PUT, FTP uploading, kerberos, HTTP form based upload, proxies, cookies, user+password authentication, file transfer resume, http proxy tunneling and more!

PHP: exec command to get std errors

By appending 2>&1 at the end of the command will redirect errors from stderr to stdout.
Example:
If you run a simple command like cc at the command prompt, you would get the output as following

 $ cc  
 i686-apple-darwin10-gcc-4.2.1: no input files  
 $  

If u run the same command using PHP exec command

 $cmd = "cc";  
 exec($cmd,$out);  
 print_r($out);  

The output would be and empty array:

 Array ( )  

So, In order to get the error string as well, we need to append 2>&1

 $cmd = "cc 2>&1";  
 exec($cmd,$out);  
 print_r($out);  

The output will print:

 Array ( [0] => i686-apple-darwin10-gcc-4.2.1: no input files )  

Mac: location of Apache web server logs

The following location contains error_log for apache web server in Mac machines

 /var/log/apache2/  

Mac: Flush DNS cache in Snow Leapord

Run the following command in the terminal
sudo dscacheutil -flushcache

For Windows:
ipconfig /flushdns

HTML: Open link in a new window

The key to use is target="_blank"
Eg:

 <a  target="_blank" href="http://glidingphenomena.blogspot.com/">
My Blog
</a>  

MySQL : Sort by Date and Time together when there are in different columns

Suppose you have date and time in two different columns of your table.
We can sort date and time together by using the ADDTIME function.

 select * from mytable ORDER BY ADDTIME(mydate, mytime);  

You can also use the ADDTIME in the select clause to get data and time together.

 select ADDTIME(mydate, mytime), city from mytable  

jQuery : Scroll to top/bottom of a specific DIV

Scroll to the bottom of the div:

 $jq('#divWithOverflowAuto').animate({   
         scrollTop: $jq('#divWithOverflowAuto')[0].scrollHeight}  
      );  
 }  

Or you can use:

 $jq('#divWithOverflowAuto').animate({   
   scrollTop: $jq('#divWithOverflowAuto').attr('scrollHeight')}  
 );  
}  

Scroll to the top of the div:

 $jq('#divWithOverflowAuto').animate({   
         scrollTop: 0 }  
      );  
 }  

Matlab: Vector product, multiply 2 column matrices, "element-wise" multiplication

If we have 2 column matrices A, B.
>>A = [10;20;30]
A =
10
20
30

>> B = [1;2;3]
B =
1
2
3

>> A+B
ans =
11
22
33

>> A*B
??? Error using ==> mtimes
Inner matrix dimensions must agree.

In order to perform "element-wise" operations, we have to use ".", so for multiplication ".*", division "./"

>> A.*B
ans =
10
40
90

>> A./B
ans =
10
10
10

CakePHP : Error: The requested address “/” was not found on this server

I was moving my cakephp application to a new server and had this issue: Error: The requested address “/” was not found on this server.

The following keys might resolve your issue:

1. Check your DATABASE_CONFIG (/app/config/database.php)
2. Delete all the cache files from all of your tmp subfolders (/app/tmp)
3. Make sure your /app/tmp folder (and all of its sub folders) are writable

If you still have issues with the app, you might have to change the debug switch to 2 or 3 in the /app/config/core.php

Find the line which says "Configure::write" and replace with the following:
Configure::write('debug', 3);

This would spit all the errors on your webpage. You can debug from there.