50 Fun Facts About Linux

Tux, the Linux mascot, is which kind of animal, chosen after Linus Torvalds said one bit him in Canberra?

A penguin was announced as the mascot in 1996. The name Tux nods both to Torvalds' UniX and to the tuxedo the bird appears to wear.

Which smartphone operating system is based on a modified Linux kernel but ships without the usual GNU software?

Android pairs the Linux kernel with Google's own userland, including a C library called Bionic, instead of the GNU one.

In which Nordic country was Linus Torvalds a university student when he began writing the Linux kernel?

Finland has a Swedish-speaking minority that includes the Torvalds family, which makes Sweden the usual wrong guess. He attended the University of Helsinki from 1988 to 1996.

In November 2017, Linux became the only operating system left on the TOP500, a twice-yearly ranking of which machines?

Supercomputers on the list have all run Linux since the last two holdouts, IBM machines running AIX, dropped off that month.

Which NASA helicopter, the first aircraft to make a powered flight on another planet, ran a Linux operating system?

Ingenuity ran Linux on a Qualcomm Snapdragon 801 processor. Planned for only five flights on Mars, it completed 72.

Which Microsoft boss said in 2001 that Linux was 'a cancer' in the intellectual property sense?

Steve Ballmer changed his stance in 2016, saying he supported his successor Satya Nadella's open-source commitments.

Which version-control system did Linus Torvalds write in 2005 after Linux kernel developers lost free use of BitKeeper?

Git is British slang for an unpleasant person, and Torvalds joked that he names all his projects after himself.

Which Linux distribution is named after a Nguni philosophy often translated as 'humanity to others'?

Ubuntu was named by its founder, Mark Shuttleworth, for his South African roots and to emphasize community.

Which keyboard shortcut stops a running command in a Linux terminal by sending it the SIGINT signal?

Ctrl+C makes the active program receive SIGINT, the interruption signal. A program can catch it to tidy up first, but most simply quit.

Which credit-card-sized British computer, created to teach computing in schools, runs Linux as its recommended system?

The Raspberry Pi went on sale in 2012 for $35 and later passed the ZX Spectrum as the best-selling British computer of all time.

Which teaching operating system by Andrew Tanenbaum was Linus Torvalds using when he began to write the Linux kernel?

Minix's creator opened a famous 1992 newsgroup thread titled 'LINUX is obsolete', arguing that a monolithic kernel was a giant step back into the 1970s.

Which programmer launched the GNU Project in 1983, whose free tools were later combined with the Linux kernel?

Richard Stallman argues that the combined system should be called GNU/Linux, to credit the project whose software surrounds the kernel.

What name did Linus Torvalds want for Linux before an FTP server administrator renamed the project without asking him?

Freax blended 'free', 'freak' and the letter x. Ari Lemmke, who helped run the server, thought it a poor name and filed the code under 'Linux' instead.

Which copyleft terms, replacing a ban on commercial distribution, have covered the Linux kernel since 1992?

The General Public License lets anyone sell or change the kernel, provided their changes are shared on the same terms. Torvalds called the switch 'definitely the best thing I ever did'.

Which chip maker did Linus Torvalds call the single worst company the Linux kernel developers had dealt with?

Nvidia drew the insult, delivered with a raised middle finger, during a 2012 talk Torvalds gave at Aalto University.

Which Linux distribution, founded by Ian Murdock in 1993, names every release after a Toy Story character?

Debian keeps its permanently unstable branch under the name Sid, after the neighbourhood child who destroys toys.

Which North Carolina open-source company, known for its enterprise Linux, did IBM agree to buy for $34 billion?

Red Hat is named for a red Cornell lacrosse hat that co-founder Marc Ewing wore at university, a gift from his grandfather.

Which rolling-release Linux distribution, begun by Judd Vinet, installs software with a tool called Pacman?

Arch Linux puts simplicity of design ahead of polished point-and-click tools, so even Pacman has no official graphical front-end.

Which free image editor did Larry Ewing use in 1996 to draw Tux, the mascot of Linux?

GIMP was at version 0.54, its first public release, when Ewing drew his contest entry. His only condition for reuse was a credit for himself and the program.

Which handheld gaming computer, released in 2022, runs Windows games on Linux through a layer called Proton?

The Steam Deck followed Valve's earlier Steam Machines, whose shortage of Linux games led the company to invest in Proton.

Which two-letter Linux command lists the files in a directory, the job that dir does in MS-DOS?

The ls command is short for 'list', a name inherited from the earlier Multics system. With no path given, it shows the files of the working directory.

Which Linux command changes the working directory and is built into the shell instead of being a separate program?

The cd command has to live inside the shell: a separate program would run as a child process, which is normally prevented from changing its parent's state.

Which three-letter Linux command prints the full path of the working directory to the terminal?

The pwd command is short for 'print working directory'. Its ancestor on the Multics system was the short name of a command called print_wdir.

Which Linux search command began as a private tool of Ken Thompson's and prints every line matching a pattern?

The name grep comes from g/re/p, an instruction in the ed editor that stands for global, regular expression, print.

Which Linux command shows the reference page for another command, cited in forms such as ftp(1) or printf(3)?

The man command formats each page and hands it to a pager program for display. The number in brackets names the section of the manual the page sits in.

Which Linux command lets a permitted user run one command as the administrator after entering their own password?

The sudo logo nods to an xkcd comic strip in which an order for a sandwich is accepted only once the word is put in front of it.

Which Linux command writes one file to the screen, or several files end to end in the order given?

The cat command gets its name from catenate, a variant form of concatenate. Naming just one file, so that its content shows on the monitor, is a common use.

Which Linux command deletes files and, given the options -rf, removes whole directory trees without asking first?

The rm command only unlinks a file instead of wiping it, so the data can sometimes be recovered with specialized tools. There is no recycle bin to fall back on.

Which Linux command sends a signal, by default SIGTERM, to a running process identified by its PID number?

The kill command is something of a misnomer: its default signal merely requests that the process exit, and other signals have nothing to do with ending anything.

Which Linux archiving command was originally developed for magnetic tape, a storage medium with no file system?

The name tar is short for 'tape archive'. A file it writes is nicknamed a tarball, and it records each file's ownership, timestamps and permissions.

Which symbol, placed between two Linux commands, feeds the output of the first into the second as its input?

The vertical bar is known as a pipe. Ken Thompson added the feature to the Unix shell in 1973 'in one feverish night', as his colleague Douglas McIlroy put it.

Which two-letter Linux command renames a file, or carries it to another directory when given a different destination?

The mv command does no copying when source and destination share a file system: it simply renames, leaving the timestamp untouched.

Which Linux command opens an encrypted login session on a remote machine, replacing the plaintext Telnet and rsh?

The ssh command was designed in 1995 by Tatu Ylönen, to hide the passwords that older remote-login tools sent across the network unprotected.

Which keyboard key makes a Linux shell complete a partly typed filename, or list the matches when several fit?

The Tab key gives the feature its usual name, tab completion. It works on commands and their arguments as well as on filenames.

Which shell, the default login shell on many Linux distributions, has a name that puns on the earlier Bourne shell?

Bash is short for 'Bourne Again SHell'. Brian Fox created it in 1989 for the GNU Project as a free alternative to the proprietary original.

Which Linux text editor, begun by Bram Moolenaar, has a licence encouraging happy users to donate to children in Uganda?

Vim first stood for 'Vi IMitation'. The author changed it to 'Vi IMproved' once its features had grown beyond those of a clone of the older editor vi.

Which Linux background scheduler runs commands at set times, reading each job's minute, hour and day from five fields?

The name cron comes from Chronos, the Greek word for time. Its jobs are listed in files known as crontabs, short for cron tables.

Which init system, begun in 2010 by Lennart Poettering and Kay Sievers, was adopted by most major Linux distributions?

The systemd design ignited controversy in the free-software community, where critics call it overly complex and a breach of the Unix philosophy.

In a Linux permission string such as rwxr-xr-x, what does the letter x allow a user to do with a file?

Execute it, meaning run it as a program. On a directory the same letter does a different job: it lets a user reach the files inside if their names are known.

Which special permission, usually set on the Linux /tmp directory, stops users deleting each other's files?

The sticky bit once told the system to keep a finished program's code in swap space, so that it started faster next time. That use is obsolete, but the name has stuck.

In a Linux path, which single character names the top-level directory that contains every other file and folder?

Slash, written /, marks the top of a single tree that holds every disk. Under Windows, by contrast, each partition is given its own drive letter.

Which top-level Linux directory does the Filesystem Hierarchy Standard reserve for system-wide configuration files?

/etc was called the 'etcetera' directory in early Bell Labs documents, because it held whatever did not belong anywhere else.

Which top-level Linux directory holds each ordinary user's personal files, a job that /usr did on early Unix systems?

/home keeps saved files and personal settings in one folder per user. The name /usr is a leftover from the days when it did that job.

Which special Linux file discards all data written to it, earning the nicknames bit bucket and black hole?

/dev/null reports every write as a success while throwing the data away, and anything that reads from it gets an immediate end-of-file.

Which Linux directory is a virtual filesystem, generated on the fly, with a numbered folder for each running task?

/proc is mounted at boot instead of being stored on disk. The kernel uses it to show its internal data as files, and even to accept changes to some settings.

Which Linux data structure records a file's owner, permissions and disk block locations, but never the file's name?

An inode is found by number, not by name. Names are kept in directories instead, which is how one file can carry several equivalent names.

Which journaling filesystem, a common Linux default, became stable in the kernel released on Christmas Day 2008?

ext4 is backward-compatible with ext3 and ext2, so a disk in either older format can be mounted as if it were the newer one.

Which Linux command sets a file's permissions, accepting either octal digits such as 755 or symbols such as u+x?

The name chmod is short for 'change mode', where a file's mode means its permissions and special flags taken together.

Which username belongs to the Linux superuser, the account with a user ID of zero that holds every permission?

The root name is only a convention: the ID is what counts. BSD systems often add a twin account called toor, the same word written backward.

Which three-digit octal mode gives every permission on a Linux file to its owner, its group and all other users?

777 is three sevens because each digit adds up read (4), write (2) and the right to run (1), once for each class of user.