Apache errors and the approach to solve it Premature end of script headers 500 Internal Server Error The specified CGI application misbehaved by not returning a complete set of HTTP headers. Some troubleshooting tips: i) Check /var/log/apache2/error.log (in ubuntu, check the respective apache error log location for the messages) ii) Check if the content type of the page is correctly set for the html content output. print "Content-type: text/html\n\n"; iii) Check if a valid permission has been given for the file to get executed. The file need permission 755 for it to be executed on the server. iv) Check if the configuration path, inclusion path are set correctly in the referenced programs

Apache Permission Denied Error can be caused due to one of many configuration mistakes listed below Check the apache configuration settings i) The first is the reference to folder where cgi or perl files will reside and its execute permission settings

 <ScriptAlias /cgi-bin/ /usr/local/cgi-bin/>
 <Directory "/usr/local/cgi-bin">
     AllowOverride None
     Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
     Order allow,deny
     Allow from all
 </Directory>

ii) The second is the proper add handlers that are set for the file execution

AddHandler cgi-script .cgi .pl
<Files ~ "\.pl$">
    Options +ExecCGI
</Files>
<Files ~ "\.cgi$">
   Options +ExecCGI
</Files>

Check the apache error log for any messages (/var/log/apache2/error.log).

GRUB stands for GRand Unified Bootloader. This is to enable the listing of multiple operating systems so the users could choose the OS of their choice. To change the menu order we need to edit a file called menu.lst # vi /boot/grub/menu.lst Look for a line "default 0". This is the option to indicate that the first menu on the list should be loaded by default. In order for you to set the default menu content in the GRUB loader that needs to get started you can set this parameter. This is of the form "default <ID>" where ID = N -1. If there are 4 list items in the menu and if you want to load the 4th item by default, you need to set this configuration setting to "default 3". Another option for you is to have the menu list with the entry "savedefault = true". This would enable the last used menu entry to get loaded during the next boot.

How to access USB Flash Drive? To know the drives and their partition you need to execute # fdisk -l Another option is to list the last 5 entries from /dev to know what devices got attached $ ls -ltr /dev | tail And another option is to use the lsusb command. USB Flash drive will normally be listed down as /dev/sdb1 (more…)

The help pages state ... su - run a shell with substitute user and group id's sudo - execute a command as another user (or root) When 'sudo' is used with a command, the command gets executed with privileges set for the user and the group she belongs to. If a password is required and if it is given initially, the session will be valid depending on the time set for each session and the user needn't have to type the password within that duration. /etc/sudoers is the location where permission settings for sudoers are being set. (more…)

It is often advisable not to disclose information than is necessary when web request are made to Apache server. By default, Apache displays the version of the server, modules loaded in the server and the version of PHP if PHP is configured with Apache. In httpd.conf file, set the following directives. ServerSignature Off ServerTokens ProductOnly By default, ServerSignature is set to Off and ServerTokens is set to Full in most Linux distros.