Most programs will return an exit status of 0 if the program was successful, while a non-zero exit status usually indicates an error. You can find the exit status or exit code of the previously executed command by accessing the “$?” shell variable. $ COMMAND $ echo $? Typically when a command terminates on a [...]

For any number of reasons you may want to know the parent process ID of the current Bash script. You can find the parent process of the current Bash script or shell by printing the ‘$PPID‘ shell variable. $ echo $PPID20341

In order to control or monitor background child processes from a shell script you will need to know the PID of the child. Bash stores the PID of the last process executed in the “$!” shell variable. If you start a background process in an interactive shell it will output the PID of the child. [...]

In many cases you will need to determine the PID of a current Bash script or shell. Bash stores a specific variable that allows you to view the process ID of the current shell “$$‘. You can echo the $$ to print the current PID. $ echo $$23490

It is often necessary to have the ability to SSH between your Linux Host and your Guest virtual machines. In VirtualBox you can do this by simply configuring a second network interface on the Guest. This type of setup will not only allow SSH sessions between Host and Guest, but also between separate Guests themselves. [...]

In many cases it can be helpful to access text from within a PDF file but accomplishing this can be next to impossible. Luckily in Linux there is a command line program called pdftotext which is included with the xpdf package. This first step is making sure that the xpdf package is installed. In Ubuntu [...]

VirtualBox makes it easy to share folders between the host OS and various guest virtual machines, but it can be difficult to remember the exact way to go about mounting the shared folder within a guest VM. Here is the way to do it correctly. First off make sure you have installed VirtualBox guest additions. [...]