Commands by foobarnl (1)

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Find default gateway

Quick HTML image gallery from folder contents
Setting: You have a lot of jpg files in a directory. Maybe your public_html folder which is readable on the net because of Apache's mod_userdir. All those files from the current folder will be dropped into a file called gallery.html as image tags that can be viewed within a web browser locally or or over the Internet. Original: $find . -iname "*.jpg" -exec echo "" >> gallery.html \;

Duplicate several drives concurrently
If you have some drive imaging to do, you can boot into any liveCD and use a commodity machine. The drives will be written in parallel. To improve efficiency, specify a larger block size in dd: $dd if=/dev/sda bs=64k | tee >(dd of=/dev/sdb bs=64k) | dd of=/dev/sdc bs=64k To image more drives , insert them as additional arguments to tee: $dd if=/dev/sda | tee >(dd of=/dev/sdb) >(dd of=/dev/sdc) >(dd of=/dev/sdd) | dd of=/dev/sde

Start a new command in a new screen window
If you are already running screen then you often want to start a command in a fresh window. You use this alias by typing 's whatever' from your command line and 'whatever' starts running in a new window. Good with interactive commands like info, vim, and nethack.

urldecoding with one pure BASH builtin
You can use ordinary printf to convert "%23%21%2fbin%2fbash" into "#!/bin/bash" with no external utilities, by using a little known printf feature -- the "%b" specifier converts shell escapes. Replace % with \x and printf will understand the urlencoded string. BASH's printf has an extension to set a variable directly, too. So you get to convert urlencoded strings from garble to plaintext in one step with no externals and no backticks.

Find the package that installed a command

Compute running average for a column of numbers
This is an on-line algorithm for calculating the mean value for numbers in a column. Also known as "running average" or "moving average".

Shuffle mp3 files in current folder and play them.
* grep -i leaves only mp3 files (case insentitive) * sort -R randomizes list (may use GNU 'shuf' instead). * the sed command will add double quotes around each filename (needed if odd characters are present)

Add a line to a file using sudo
This is the solution to the common mistake made by sudo newbies, since $ sudo echo "foo bar" >> /path/to/some/file does NOT add to the file as root. Alternatively, $ sudo echo "foo bar" > /path/to/some/file should be replaced by $ echo "foo bar" | sudo tee /path/to/some/file And you can add a >/dev/null in the end if you're not interested in the tee stdout : $ echo "foo bar" | sudo tee -a /path/to/some/file >/dev/null

A nice way to show git commit history, with easy to read revision numbers instead of the default hash


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