Commands tagged truncate (1)

  • If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes. The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast). Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc... Command tested under Linux. Show Sample Output

    truncate --size 1G bigfile.txt
    ynedelchev · 2015-02-26 11:56:27 0

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Install pip with Proxy
Installs pip packages defining a proxy

quick integer CPU benchmark
This is a quick and dirty way to generate a (non-floating-point) CPU-bound task to benchmark. Adjust "20" to higher or lower values, as needed. As a benchmark this is probably a little less bogus than bogomips, and it will run anywhere 'bc' does.

find all active IP addresses in a network
You send a unicast ICMP packet to each host. Many firewalls will drop that ICMP. However, in order to send the ICMP, you'll have first done an ARP request and the remote machine is unlikely to ignore that, so the computer will be in your ARP table.

Decrypt passwords from Google Chrome and Chromium.
Read this before you down voting and comment that it is not working -> Wont work on latest versions ~75> since database file is locked and has to be decrypted. This is useful if you have an old hdd with a chrome installation and want to decrypt your old passwords fast.

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

Securely destroy data on given device hugely faster than /dev/urandom
This command generates a pseudo-random data stream using aes-256-ctr with a seed set by /dev/urandom. Redirect to a block device for secure data scrambling.

This command can be used to extract the IP address of the network.
can be used within a script to configure iptables for example: iface=$2 inet_ip=`ifconfig "$iface" | grep inet | cut -d: -f2 | cut -d ' ' -f1` ipt="sudo /sbin/iptables" ......................... ---------------------------------------------------------------------------------------------------------------- $ipt -A INPUT -i $iface ! -f -p tcp -s $UL -d $inet_ip --sport 1023: --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT ---------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------- $ipt -A OUTPUT -o $iface -p tcp -s $inet_ip -d $UL --sport 3306 --dport 1023: -m state --state ESTABLISHED,RELATED -j ACCEPT -----------------------------------------------------------------------------------------------------------------

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Make vim open in tabs by default (save to .profile)
I always add this to my .profile rc so I can do things like: "vim *.c" and the files are opened in tabs.

list files recursively by size

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