Archive for Computer Science

Windows 7 DWM (dwm.exe) High CPU Performance Issues

On this system, I’m blessed with a triple-headed setup: I have three nice LCD monitors on my desktop which create a panoramic view of my terminal screens. I’m also cursed with Windows 7 and it’s [many] flaws. Lately, I’ve been having an issue with Windows 7’s Desktop Window Manager (DWM, shown as dwm.exe in Task Manager) consuming large amounts of CPU and RAM resources. After a bit of snooping around, I found a simple fix:

1.) Click the START button.
2.) Type “powershell” into the “Search programs and files” box.
2a.) If you see a menu item for PowerShell, open it.
2b.) If you do not see a menu item for PowerShell, this won’t work for you.
3.) Type “net stop uxsms”
3a.) Try this if you want a stripped-down version of your ALT+TAB and fewer bits of eye candy. It’s just like WinXP, and runs quicker. If your ALT+TAB was slow, it should now zip along quite nicely.
3b.) If you want your effects and nicer ALT+TAB screens back, type “net start uxsms” and you should be good to go.

The BASIC Equivalent of Hell

10 PRINT “This is the song that doesn’t end.”
20 GOSUB 50
30 PRINT “Some people started singing it, not knowing what it was.”
40 PRINT “And they’ll continue singing it forever, just because….”
45 GOTO 10
50 PRINT “Yes, it goes on and on, my friend.”
60 RETURN

Add New Domains to Apache On Command Line

I had a need to add several domains to Apache for a client about an hour ago, and instead of copying, pasting, changing, and repeating, I opted to script it. It’s very simple (read: not secure for multiple users in production), but served my needs today beautifully. Feel free to clean it up and use it, change it, whatever.

The primary reason this is added is to show how CLI scripts can be made to wait for and accept user input. Note the use of STDOUT and STDIN in the script. This is something that I’ve found to be quite unfortunately overlooked in a lot of CLI scripts. Using this, you can make a PHP CLI script interactive, instead of requiring arguments to be passed on the command line.

Also, note that this particular script wasn’t needed for user creation, DNS, or anything of the like. Strictly for adding an Apache directive for the domain.

(The code itself is indented, but I’m learning more and more why Philip Olsen scoffed at me for installing Serendipity last year. Eventually my error in judgment shall be rectified.)


#!/usr/bin/php
<?php

if(trim(`whoami`) != 'root') die("You must be root to run this command.\n");

fwrite(STDOUT,"Domain to be added: ");
$domain = trim(fgets(STDIN));

fwrite(STDOUT,"Username to use for this domain: ");
$user = trim(fgets(STDIN));

fwrite(STDOUT,"Group to use for this domain: ");
$group = trim(fgets(STDIN));

fwrite(STDOUT,"Path to use for the web root of this domain: ");
$path = trim(fgets(STDIN));

fwrite(STDOUT,"Server administrator's email address to use: ");
$email = trim(fgets(STDIN));

echo "Writing.... ";

$newHost =<<<TXT

NameVirtualHost *:80
<VirtualHost *:80>
ServerAdmin $email
DocumentRoot $path
ServerName $domain
ServerAlias www.$domain
ErrorLog logs/$domain-error_log
CustomLog logs/$domain-access_log combined
<IfModule mod_suphp.c>
suPHP_Engine On
suPHP_ConfigPath "/etc/"
suPHP_AddHandler x-httpd-php
suPHP_AddHandler php5-script .php
suPHP_UserGroup $user $group
</IfModule>
</VirtualHost>
TXT;

file_put_contents('/etc/httpd/conf/httpd.conf',$newHost,FILE_APPEND);

echo "Done.\n";

fwrite(STDOUT,"Should I restart Apache now for the changes to take effect? (y/N) ");
if(preg_match('/^ye?s?$/i',trim(fgets(STDIN)))) {
exec('service httpd restart');
echo "Apache restarted.\n";
}

?>

Finding Which php.ini Is Loaded

This is actually a throwback to the post Overriding PHP Settings, but is presented here separately due to the number of times the question is asked.

If you’re on a *NIX-based system and are trying to figure out which php.ini is being loaded by the CLI, simply run the following command:

ls -l `/bin/env php -i | grep "Loaded Configuration File" | sed 's/.*=> //g'`

If you want to edit the file right from that command, simply replace ‘ls -l’ with an editor of your choice, such as:

vi `/bin/env php -i | grep "Loaded Configuration File" | sed 's/.*=> //g'`

Script to Automate Multi-User Development Permissions In Linux: Part II

As discussed in the previous entry a few moments ago:

While deploying a large virtual server for a client, one of the obstacles they had faced with their previous setup was multi-user permissions with regard to everyone modifying files and directories with their own FTP and/or SSH accounts. Unfortunately, for reasons that won’t be divulged here (quite frankly because I don’t know), and even after I suggested alternatives such as updating policies and standard operating procedures, the client opted to continue using previous methods, but still wanted a resolution to issues they faced in their multi-developer environment.

The following simple Bash script is called directly via a cron job every fifteen minutes:


#!/bin/bash

mode='4771';

# The directory in which "multiUserPermissionsFix" resides.
dir='/danbrown/scripts/';

if ( test "`whoami`" != 'root' ); then
echo "$0 MUST be run as root!";
exit -1;
fi;

if ( test "$1" == "" ); then
echo "You must specify the base directory.";
exit -1;
fi;

if ( test "$2" == "" ); then
echo "You must specify the group ownership to set.";
exit -1;
fi;

if [ -d "$1" ]; then

echo -n "Verifying ownership and group ownership of all files.... ";
chown -R $2:$2 $1;
echo "Done.";

cd $1;

echo -n "Resetting permissions now.... ";
find . -type d -exec chmod $mode '{}' \;
# for i in `find . -type d`; do
# chmod $mode $i;
# done;
echo "Done.";

echo -n "Verifying ownership requirements.... ";
find . -type d -exec chmod o+s '{}' \;
# for i in `find . -type d`; do
# chmod o+s $i;
# done;
echo "Good.";

echo -n "Verifying group requirements.... ";
find . -type d -exec chmod g+s '{}' \;
# for i in `find . -type d`; do
# chmod g+s $i >> /dev/null 2>&1
# done;
echo "Good.";

if [ "$?" != "0" ]; then
echo "That group does not exist!";
exit -1;
fi;

echo -n "Fixing bad permissions.... ";
$dir/multiUserPermissionsFix $1;
echo "Done.";

echo "Task Complete.";

exit 0;

else

echo "That directory doesn't exist!";
exit -1;

fi;

Script to Automate Multi-User Development Permissions In Linux: Part I

While deploying a large virtual server for a client, one of the obstacles they had faced with their previous setup was multi-user permissions with regard to everyone modifying files and directories with their own FTP and/or SSH accounts. Unfortunately, for reasons that won’t be divulged here (quite frankly because I don’t know), and even after I suggested alternatives such as updating policies and standard operating procedures, the client opted to continue using previous methods, but still wanted a resolution to issues they faced in their multi-developer environment.

To address one particular issue, I wrote the following very simple Bash script and set it on a cron running every 15 minutes, dumping all errors and standard output to a black hole.


#!/bin/bash
# Name: multiUserPermissionsFix
# Mode: 0755

function usage {
echo "USAGE: $0 base_directory";
exit -1;
}

# If we didn't even bother to pass an argument to this script, die.
if ( test "$1" == "" ); then
usage;
fi;

# Set up find correctly.
export IFS=$'\n';

# If this is a valid directory, do the work.
if [ -d "$1" ]; then

# Force a trailing slash - workaround for symlinked directories, etc.
d="$1/";

# Find and fix all file permissions --- but ignore all 'cache' cases.
find . -type f -not -path "*cache*" -exec chmod 0664 '{}' \;

exit 0;

# If it wasn't a valid directory passed to this script, die on an error.
else
echo "That directory does not exist!";
exit -1;
fi;

This script is actually not called directly, but instead by a parent script. It recursively runs through all files and sets the permissions to 0664 (owner read/write, group read/write, world read) so that users within the group can update or delete the files within the directory without requiring administrative intervention.