Allow to read password in a script without showing the password inserted by the user

List files above a given size threshold.

This is a very powerful command line tool to gather statistics for a Linux system.

http://dag.wieers.com/home-made/dstat/

Reads a username from

This command will display only the hosts that are active in the network.

These are simple shortcuts to pause and continue terminal output, works in most terminals and screen multiplexers like screen. You can use it to catch something if things change too fast, and scroll with Shift + PgUp PgDown. On linux console ScrollLock can also be used.

Echos the number of seconds from the current time till the specified time (Example in command is (2**31-1)) aka the Unix epoch. Just replace that number with the specified date (in seconds past Jan. 1st 1970) and it will return the seconds.

NOTE: Only works in bash

This will perform one of two blocks of code, depending on the condition of the first. Essentially is a bash terniary operator.

To tell if a machine is up:

Because of the bash { } block operators, you can have multiple commands

Tips:

Remember, the { } operators are treated by bash as a reserved word: as such, they need a space on either side.

If you have a command that can fail at the end of the true block, consider ending said block with 'false' to prevent accidental execution

Requires ImageMagick. Takes a screenshot 5 seconds after it's run and saves it as desktop_screenshot.jpg Particularly handy when made into a menu option or button.

You can use this to loop any command to periodically see the output.

Alternatively, you can put it in a simple shell script to save typing!

#/!bin/bash

while true; do $1; sleep $2; done;

But who knows to delete the rest of the lines?

I want only "string".

Com o fuser voce descobre quem esta ocupando o dispositivo.

Depois pode desativar o servico manualmente. Ou se necessario, matar o servico com Kill, usando o numero PID.

ex: kill -9 1768

fonte: http://www.vivaolinux.com.br/dica/Desmontando-um-dispositivo-ocupado

This simply pulls the password out of the database for the given mail name for ease of use in testing emails that you would not normally have access to.

It can resume a failed secure copy ( usefull when you transfer big files like db dumps through vpn ) using rsync.

It requires rsync installed in both hosts.

rsync --partial --progress --rsh=ssh $file_source $user@$host:$destination_file local -> remote

or

rsync --partial --progress --rsh=ssh $user@$host:$remote_file $destination_file remote -> local

Are there any creative pieces of music that can be created using beep and the shell? I'd love to hear it!

This starts an X server using Xvfb(1) (no graphics hardware required), then starts a VNC server on the display. Change :1 if there's a conflict with an existing display, and change 800x600x24 to suit your tastes (24 is the bit depth, 800x600 is the size). This command obviously requires X be installed, and also x11vnc(1); both are available via your favourite package manager. You can also use another VNC server of your choosing, as long as DISPLAY is set to the display of Xvfb(1). To change your desktop environment (the default is twm(1), which is rather fail), you can add it to your ~/.xinitrc file (see the startx(1) manpage for details).

pings a server once per second, and beeps when the server is unreachable.

Basically the opposite of:

which would beep when a server IS reachable.

You could also substitute beep with any command, which makes this a powerful alternative to ping -a:

which would output the date and time every sec until the ping failed, in which case it would echo.

Notes:

Requires beep package.

May need to run as root (beep uses the system speaker)

Tested on Ubuntu which doesn't have beep out of the box...

Depending on the installation only certain of these man pages are installed. 12 is left out on purpose because ISO/IEC 8859-12 does not exist. To also access those manpages that are not installed use opera (or any other browser that supports all the character sets involved) to display online versions of the manpages hosted at kernel.org:

perror should be installed if mysql-server package is installed

Let me suggest using wget for obtaining the HTTP header only as the last resort because it generates considerable textual overhead. The first ellipsis of the sample output stands for

Spider mode enabled. Check if remote file exists.

--2009-03-31 20:42:46-- http://www.example.com/

Resolving www.example.com... 208.77.188.166

Connecting to www.example.com|208.77.188.166|:80... connected.

HTTP request sent, awaiting response...

and the second one looks for

Length: 438 [text/html]

Remote file exists and could contain further links,

but recursion is disabled -- not retrieving.

Without the -dump option the header is displayed in lynx. You can also use w3m, the command then is