Commands by juanmi (4)

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The scene in the Shining (Stanley Kubrick)
Let's take a rest. How about watch a horror? The Shining http://en.wikipedia.org/wiki/The_Shining_(film)

execute your commands and avoid history records
$ secret_command;export HISTCONTROL= This will make "secret_command" not appear in "history" list.

get a rough estimate about how much disk space is used by all the currently installed debian packages
The vaule is expressed in megabytes

Drop or block attackers IP with null routes
Someone might attack on your system. You can drop attacker IP using IPtables. However, you can use route command to null route unwanted traffic. A null route (also called as blackhole route) is a network route or kernel routing table entry that goes nowhere. Matching packets are dropped (ignored) rather than forwarded, acting as a kind of very limited firewall. The act of using null routes is often called blackhole filtering.

clean up memory of unnecessary things (Kernerl 2.6.16 or newer)
run sync first to flush useful things out to disk!!! To free pagecache: echo 1 > /proc/sys/vm/drop_caches To free dentries and inodes: echo 2 > /proc/sys/vm/drop_caches To free pagecache, dentries and inodes: echo 3 > /proc/sys/vm/drop_caches

Compare an archive with filesystem
and you quickly know the files you changed

Prepend text to a file

mount a cdrom

Recursively Find Images, Convert to JPEGS and Delete
Simple command to convert a large number of images into jpeg-format. Will delete originals after conversion.

Rename files in batch


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