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Which Linux characters do beginners use most?

Learning all of the contexts in which non-alphnumeric characters have meaning can take years. Here we start with the most common.
  1. Context - Describe how and why symbols have meaning in different contexts.
  2. GNU Bash manual - Provide a link to the official documentation for bash.
  3. Cheat sheet - Access a Linux Cheat Sheet to trigger your memory.
  4. Practice - See each of 9 special characters in action.
  5. Next: config files - Find Linux configuration files.
Paul Alan Davis, February 11, 2017
Updated: August 11, 2018
Master symbols across different contexts and you will master Linux.

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Memorize a few symbols then know where to look them up quickly


Video Tutorial

Which Linux characters do beginners use most? | Linux Tutorial for Beginners (4:31)

Videos can also be accessed from our Full Stack Playlist 2 on YouTube.

Code Examples and Video Script

Welcome. Today's question: Which Linux characters do beginners use most?

I'm Paul, and believe me, I know that interpreting symbols in Linux is a challenge for those coming from Mac and Windows.

Tackling them all is unrealistic and our goal really is to navigate Linux enough to install a software stack for Data Science.

Step 1 - Context Defines What Symbols Do

So in this tutorial, I'll cover must-know characters and keystrokes and prepare you to look the others up.

In any language, words have meaning depending on context, right? Well, characters in Linux, and the bash shell in particular, are the same. And because there are too many to memorize, I'll point you to two sources for help, an online Bash Manual, and a Cheat Sheet summarizing non-alphanumeric characters.

Then we'll practice with these nine essentials.

  • - / ~ ; # . > | Ctrl-c

(And practice with a few other commands).

  • sleep
  • bash
  • help
  • whatis
  • clear
  • ls
  • wc
  • less
  • exit

In the next video, we'll cover the basics of configuration files.

Step 2 - GNU Bash Manual

I'll hop over to a local Linux test server running Debian, and summarize what we'll cover here using whatis. Then I'll change directories to /notes, list files, and we'll open one in a minute.

paul@fullstack:~$ whatis sleep whatis less pwd ls wc exit sleep (1) - delay for a specified amount of time whatis (1) - display one-line manual page descriptions less (1) - opposite of more pwd (1) - print name of current/working directory ls (1) - list directory contents wc (1) - print newline, word, and byte counts for each file exit: nothing appropriate paul@fullstack:~$ pwd /home/paul paul@fullstack:~$ cd notes paul@fullstack:~/notes$ ls video0002.txt video0004.txt video0006.txt video0008.txt video0011.txt video0016.txt video0003.txt video0005.txt video0007.txt video0009.txt video0012.txt video0017.txt paul@fullstack:~/notes$ clear

Try an exercise, look at your keyboard and count the number of non-alphanumeric keys. So no letters, numbers or function keys.

The letter c, for example, can only mean the letter c; however, characters have many meanings, depending on context.

On my keyboard there are 32, and I went left to right and created a table shown here in less.

paul@fullstack:~/notes$ less video0016.txt
Linux non-alphanumeric characters (video 16) ## char name(s) context ## char name(s) context -- ---- ------------------- ----------- -- ---- ------------------ ----------- 1 ` backtick 17 | pipe, vertical bar redirection 2 ~ tilde directory 18 \ backslash 3 ! exclamation, bang 19 / forward slash directory 4 @ ampersand, at 20 { open curly brace 5 # number, pound, hash comment 21 } close curly brace 6 $ dollar symbol 22 [ open bracket 7 % percent 23 ] close bracket 8 ^ caret 24 " double quote 9 & ampersand 25 ' single quote, apos. 10 * asterisk, star 26 : colon 11 ( open parenthesis 27 ; semicolon commands 12 ) close parenthesis 28 ? question mark 13 _ underscore 29 < less than 14 - dash, minus, hyphen options 30 > greater than redirection 15 + plus 31 . period, dot directory 16 = equal 32 , comma video0016.txt (END)

I put common names here and the context for those I'll discuss here.

So the tilde symbol ~ comes up when we're talking about directories, pound # for comments, and for dash - it's options.

Why is it that characters have multiple meanings? First, it saves keystrokes and second, it simplifies complex instructions.

Step 2 - Find Help on Characters

You know how to access the man bash page, all 5,000 lines of it.

paul@fullstack:~/notes$ man bash
BASH(1) General Commands Manual BASH(1) NAME bash - GNU Bourne-Again SHell SYNOPSIS bash [options] [command_string | file] COPYRIGHT Bash is Copyright (C) 1989-2013 by the Free Software Foundation, Inc. DESCRIPTION Bash is an sh-compatible command language interpreter that executes commands read from the standard input or from a file. Bash also incorporates useful features from the Korn and C shells (ksh and csh). Bash is intended to be a conformant implementation of the Shell and Utilities por tion of the IEEE POSIX specification (IEEE Standard 1003.1). Bash can be configured to be POSIX-conformant by default. OPTIONS All of the single-character shell options documented in the description of the set builtin command can be used as options when the shell is invoked. In addition, bash interprets the following options when it is invoked: -c If the -c option is present, then commands are read from the first non- option argument command_string. If there are arguments after the com mand_string, they are assigned to the positional parameters, starting with

For those really hungry for bash knowledge, I suggest the free 175-page GNU Bash Manual, offered in a variety of formats.

Step 3 - Linux Cheat Sheet

I've summarized some of it in a Linux Cheat Sheet you can check out later. I'll keep improving it, so check in periodically.

Step 4 - Practice with Non-Alphanumeric Characters

The dash character in Linux

On the most used symbols for beginners. First, let's discuss dash - and view the man page for whatis.

paul@fullstack:~/notes$ man whatis
paul@fullstack:~/notes$ man whatis WHATIS(1) Manual pager utils WHATIS(1) NAME whatis - display one-line manual page descriptions SYNOPSIS whatis [-dlv?V] [-r|-w] [-s list] [-m system[,...]] [-M path] [-L locale] [-C file] name ... DESCRIPTION Each manual page has a short description available within it. whatis searches the manual page names and displays the manual page descriptions of any name matched. name may contain wildcards (-w) or be a regular expression (-r). Using these options, it may be necessary to quote the name or escape (\) the special characters to stop the shell from interpreting them. index databases are used during the search, and are updated by the mandb program. Depending on your installation, this may be run by a periodic cron job, or may need to be run manually after new manual pages have been installed. To produce an old style text whatis database from the relative index database, issue the command: whatis -M manpath -w '*' | sort > manpath/whatis where manpath is a manual page hierarchy such as /usr/man. OPTIONS -d, --debug (102 lines trimmed) AUTHOR Wilf. Fabrizio Polacco. Colin Watson. 2014-09-28 WHATIS(1)

But I could have used -h for help or -V for version.

paul@fullstack:~/notes$ whatis -h Usage: whatis [OPTION...] KEYWORD... -d, --debug emit debugging messages -v, --verbose print verbose warning messages -r, --regex interpret each keyword as a regex -w, --wildcard the keyword(s) contain wildcards -l, --long do not trim output to terminal width -C, --config-file=FILE use this user configuration file -L, --locale=LOCALE define the locale for this search -m, --systems=SYSTEM use manual pages from other systems -M, --manpath=PATH set search path for manual pages to PATH -s, --sections=LIST, --section=LIST search only these sections (colon-separated) -?, --help give this help list --usage give a short usage message -V, --version print program version Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options. paul@fullstack:~/notes$ whatis -V whatis paul@fullstack:~/notes$ clear

Of course, dash is used in other contexts as well.

The slash character in Linux

Second, slash /, so this is very basic, but slashes denote folders. The first one being the root, or the base of the directory structure.

paul@fullstack:~/notes$ pwd /home/paul/notes paul@fullstack:~/notes$
The tilde character in Linux

Next, the tilde, ~, here (pointing to output above) refers to my home directory. So this (pointing to /home/paul/notes and this ~/notes are the same place).

You can always do this to go home.

paul@fullstack:~/notes$ cd ~ paul@fullstack:~$
The semicolon character in Linux

Next, the semicolon ; character is for entering multiple commands at once.

paul@fullstack:~$ cd notes; pwd; ls /home/paul/notes video0002.txt video0004.txt video0006.txt video0008.txt video0011.txt video0016.txt video0003.txt video0005.txt video0007.txt video0009.txt video0012.txt video0017.txt paul@fullstack:~/notes$
The pound character in Linux

The pound # is a comment, meaning the rest of the line is ignored.

paul@fullstack:~/notes$ #ls paul@fullstack:~/notes$
The dot character in Linux

The dot . occurs in many contexts, but the most basic is that dot refers to the present directory. Using an ls -a shows dots here, one dot is the current directory and two dots points to one above.

paul@fullstack:~/notes$ ls -a . video0002.txt video0004.txt video0006.txt video0008.txt video0011.txt video0016.txt .. video0003.txt video0005.txt video0007.txt video0009.txt video0012.txt video0017.txt paul@fullstack:~/notes$ ls .; ls .. video0002.txt video0004.txt video0006.txt video0008.txt video0011.txt video0016.txt video0003.txt video0005.txt video0007.txt video0009.txt video0012.txt video0017.txt notes

(So listing files with one dot printed the first two lines and with two dots it printed the third).

The greater than character in Linux

The greater than symbol > is used to create a file on the fly.

For example, I could do an ls on this directory and put it one directory above, calling it lstest.txt.

paul@fullstack:~/notes$ ls . > ../lstest.txt paul@fullstack:~/notes$ less ~/lstest.txt

Then view it using less (followed by q to quit).

video0002.txt video0003.txt video0004.txt video0005.txt video0006.txt video0007.txt video0008.txt video0009.txt video0011.txt video0012.txt video0016.txt video0017.txt /home/paul/lstest.txt (END)

(So listing files with one dot printed the first two lines and with two dots it printed the third).

The pipe character in Linux

A similar symbol is pipe |, where output from one command is handed off to another.

Here we use wc to count files.

paul@fullstack:~/notes$ ls | wc -l 12
The Ctrl+c keystroke combination in Linux

And last is the keystroke combination Ctrl+c. If you ever get to the point where you're lost and don't see a command prompt, it means a program is running.

I've used one called sleep to mimic what you might see.

paul@fullstack:~/notes$ sleep 1m ^C paul@fullstack:~/notes$

Here Ctrl+c will stop that process.

Step 5 - Next: Configuration Files

We're just scratching the surface on characters here, and trying to learn enough Linux to get our software stack installed so we can start playing around with Math and Statistics in Python.

  • Client : HTML, CSS, JavaScript
  • Software : Python Scientific Stack
  • Data : PostgreSQL, MySQL
  • OS : Linux (command line), Debian

In our next video we'll talk about configuration files.

Have a nice day.

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~/ home  / tech  / full stack  / linux characters

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