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Unite pdf files
pdfunite is a part of the poppler-utils. poppler-utils package is only 150KB. The alternative - pdftk package is 14MB! Install poppler-utils if you need simple pdf operation commands like unite, separate, info, text/html conversions

Capitalize first letter of each word in a string - A ruby alternative
"-n" loops around ; "-e" executes the given quoted string ; "$_" is the current line ; "split" creates an array on white space; each item of the array is "collected" to be then "capitalized" ; the array is "joined" back into a string.

Perl Command Line Interpreter
Read, Evaluate, Print, Loop - REPL

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Displays the number of unread messages on your gmail at the top right corner of your terminal
Checks your gmail account every 30 seconds and display the number of new messages in the top right corner of the terminal. A kind of CLI "Gmail notifier" if you will. :-) This is a mashup of http://www.commandlinefu.com/commands/view/7916/put-a-console-clock-in-top-right-corner and http://www.commandlinefu.com/commands/view/3386/check-your-unread-gmail-from-the-command-line

Show Directories in the PATH Which does NOT Exist
I often need to know of my directory in the PATH, which one DOES NOT exist. This command answers that question * This command uses only bash's built-in commands * The parentheses spawn a new sub shell to prevent the modification of the IFS (input field separator) variable in the current shell

Stop long commands wrapping around and over-writing itself in the Bash shell
add the command either in /etc/profile or ~/.bash_profile so that this is available to your shell.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Securely destroy data (including whole hard disks)
GNU shred is provided by the coreutils package on most Linux distribution (meaning, you probably have it installed already), and is capable of wiping a device to DoD standards. You can give shred any file to destroy, be it your shell history or a block device file (/dev/hdX, for IDE hard drive X, for example). Shred will overwrite the target 25 times by default, but 3 is enough to prevent most recovery, and 7 passes is enough for the US Department of Defense. Use the -n flag to specify the number of passes, and man shred for even more secure erasing fun. Note that shredding your shell history may not be terribly effective on devices with journaling filesystems, RAID copies or snapshot copies, but if you're wiping a single disk, none of that is a concern. Also, it takes quite a while :)


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