All commands

Query Wikipedia by issuing a DNS query for a TXT record. The TXT record will also include a short URL to the complete corresponding Wikipedia entry.You can also write a little shell script like:

and run it like

were your first option ($1) will be used as search term.

ps returns all running processes which are then sorted by the 4th field in numerical order and the top 10 are sent to STDOUT.

When typing out long arguments, such as:

You can put that argument on your command line by holding down the ALT key and pressing the period '.' or by pressing <ESC> then the period '.'. For example:

would put '/var/www/wp-content/uploads/2009/03/ as my argument. Keeping pressing 'ALT+.' to cycle through arguments of your commands starting from most recent to oldest. This can save a ton of typing.

Prepending one or more spaces to your command won't be saved in history.

Useful for pr0n or passwords on the commandline.

Tested on BASH.

time read -sn1 (s:silent, n:number of characters. Press any character to stop)

This will issue a shutdown command to the Windows machine. username must be an administrator on the Windows machine. Requires samba-common package installed. Other relevant commands are:

net rpc shutdown -r : reboot the Windows machine

net rpc abortshutdown : abort shutdown of the Windows machine

Type:

net rpc

to show all relevant commands

Unreachable_host is unavailable from local network, but it's available from reachable_host's network. This command creates a connection to unreachable_host through "hidden" connection to reachable_host.

Waiting for your server to finish rebooting? Issue the command above and you will hear a beep when it comes online. The -i 60 flag tells ping to wait for 60 seconds between ping, putting less strain on your system. Vary it to your need. The -a flag tells ping to include an audible bell in the output when a package is received (that is, when your server comes online).

notice what happens when there is more than one unread message in a thread...

also people please dont hardcode the password when you use curl. Leave it out and curl will ask you when it runs. Please...?

Using +F will put less in follow mode. This works similar to 'tail -f'. To stop scrolling, use the interrupt. Then you'll get the normal benefits of less (scroll, etc.).

Pressing SHIFT-F will resume the 'tailling'.

If the machine is hanging and the only help would be the power button, this key-combination will help to reboot your machine (more or less) gracefully.

R - gives back control of the keyboard

S - issues a sync

E - sends all processes but init the term singal

I - sends all processes but init the kill signal

U - mounts all filesystem ro to prevent a fsck at reboot

B - reboots the system

Save your file before trying this out, this will reboot your machine without warning!

http://en.wikipedia.org/wiki/Magic_SysRq_key

This is a simple example of using proper command nesting using $() over ``. There are a number of advantages of $() over backticks. First, they can be easily nested without escapes:

versus

Second, they're easier to read, then trying to decipher the difference between the backtick and the singlequote: `'. The only drawback $() suffers from is lack of total portability. If your script must be portable to the archaic Bourne shell, or old versions of the C-shell or Korn shell, then backticks are appropriate, otherwise, we should all get into the habit of $(). Your future script maintainers will thank you for producing cleaner code.

This command will start a simple SMTP server listening on port 1025 of localhost. This server simply prints to standard output all email headers and the email body.

Use Ctrl-] to stop it.

Replace and accordingly.

I find this terribly useful for grepping through a file, looking for just a block of text. There's "grep -A # pattern file.txt" to see a specific number of lines following your pattern, but what if you want to see the whole block? Say, the output of "dmidecode" (as root):

Will show me everything following the battery block up to the next block of text. Again, I find this extremely useful when I want to see whole blocks of text based on a pattern, and I don't care to see the rest of the data in output. This could be used against the '/etc/securetty/user' file on Unix to find the block of a specific user. It could be used against VirtualHosts or Directories on Apache to find specific definitions. The scenarios go on for any text formatted in a block fashion. Very handy.

bash/ksh subshell redirection (as file descriptors) used as input to diff