Commands using head (314)

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securely erase unused blocks in a partition
This command securely erases all the unused blocks on a partition. The unused blocks are the "free space" on the partition. Some of these blocks will contain data from previously deleted files. You might want to use this if you are given access to an old computer and you do not know its provenance. The command could be used while booted from a LiveCD to clear freespace space on old HD. On modern Linux LiveCDs, the "ntfs-3g" system provides ReadWrite access to NTFS partitions thus enabling this method to also be used on Wind'ohs drives. NB depending on the size of the partition, this command could take a while to complete.

print a python-script (or any other code) with syntax-highlighting and no loss of indentation

create an emergency swapfile when the existing swap space is getting tight
Create a temporary file that acts as swap space. In this example it's a 1GB file at the root of the file system. This additional capacity is added to the existing swap space.

Show the command line for a PID, converting nulls to spaces and a newline
If you cat the file, all the parts of the command line are bunched up. If you use tr to convert the nulls to spaces, you're still left without a newline unless you add another step. This command does everything for you.

check open ports without netstat or lsof

Count lines using wc.

List the largest directories & subdirectoties in the current directory sorted from largest to smallest.

Make changes in .bashrc immediately available

Open (in vim) all modified files in a git repository
The option --porcelain makes the output of git easier to parse. This one-liner may not work if there is a space in the modified file name.

Scan Subnet for IP and MAC addresses


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