OPS102 - File Globbing, Common Commands, Text Editors

File Globbing / Ambiguous Filenames / Filename Patterns

Linux and Windows systems both allow ambiguous filenames, which use wildcard symbols to enable filename matching. The process of converting an ambiguous filename, or filename pattern, into a list of matchine filenames is called globbing or filename expansion.

On a Linux system, globbing is performed by the shell. This means that all arguments are subject to globbing, whether they're intended to be a filename argument or not.

On a Windows system, ambiguous filenames are converted into a list of filenames by the command or application. This means that arguments that are not filenames are not subject to filename expansion. However, it also means that applications must contain additional code to perform globbing.

Wildcard Symbols

Symbol	Meaning in Linux	Meaning in Windows
*	Matches zero or more characters	Matches zero or more characters
?	Matches one character	Matches one character, unless at the end of the filename or immediately before the dot preceeding the extension in which case it matches zero or one character
[list]	Matches any one of the characters within the brackets (note that it matches exactly one of the characters)	Not applicable

Examples

Pattern	Matches on Linux	Does not match on Linux	Matches on Windows	Does not match on Windows
a*	a aa aaa alpha argonaut	Alpha banana	a aa aaa alpha Alpha	banana
b*e	blue bite	red green blot	blue bite	red green blot
c[oa]t	cat cot	coat		cat cot coat (Not applicable)
d?e	due doe	duo Doe date	due doe Doe	duo date
a??	aaa abc	aa abcd	aaa abc aa	abcd

Therefore the command

 del *.pdf

on Windows, or

 rm *.pdf

on Linux will remove all files with the extension .pdf

Common Basic Commands

Here are some basic commands useful for managing the filesystem and performing basic tasks:

Linux	Windows	Description
ls	dir	Displays the contents of a directory -- by default, the current directory, or the directories specified as arguments (or a specific file, if specified).
echo	echo	Places a message on the screen (the message is given as positional arguments)
cal		Displays a simple calendar
date	date /t time /t	Displays the date/time
who	quser	Displays information about the logged in user(s)
whoami	whoami	Displays the name of the current user
clear	cls	Clears the terminal display. Note: in the Bash shell, you can also clear the screen during command entry by typing ^L (Ctrl+L)
tree	tree	Displays the filesystem hierarchy starting at the current directory (or the given directory, if an argument is provided).
mkdir	mkdir	Creates a directory/folder
rmdir	rmdir	Removes a directory/folder
rm	del	Removes/deletes one or more files. Specify -rf to recursively force delete a directory and its contents on Linux, or /s to recursively delete a directory and its contents on Windows.
cd	cd	Changes to the given directory, if one is given. If no directory is given, displays the current directory (Windows) or changes to your home directory (Linux). On Windows, a drive designator may be provided, in which case the current directory will be set on the indicated drive.
	X:	(Where X is a drive designator) Switches to the selected drive.
pwd		Prints the current working directory.
cp	copy	Copy one or more files to a new name/location.
mv	move	Moves a file from one directory to another.
mv	ren rename	Renames a file (on Linux, the filename and location are considered to be the same thing)
cat	type	Dumps the contents of a text file on the terminal (if there is a lot of text, the display will scroll; if the file is a non-text file, the results are undefined!)
more less	more	Displays a file one screen at a time. (Linux: the less command is a more powerful version of the more command, which allows things like scrolling backwards)
cut		Selects specific columns from a text file
sort	sort	Sorts a text file
diff	comp fc	Shows the differences between (text) files
uniq		Displays identical consequtive lines only once
tr		Translates/replaces/deletes occurrences of characters
grep	find	Searches files for text
find		Searches for files
touch	copy NUL: filename	Creates an empty file (Linux: if the file exists, touch will just update the date/time of modification).

Viewing Online Documentation

To find a Linux command to perform a particular function, use the apropos or man -k commands:

 apropos calendar

 man -k calendar       # same as the above!

To view information about a Linux command, use the online manual ("manpages"), accessed with the man command:

 man commandname

For example, to view the online manual page for cp, enter the command:

 man cp

On Windows, you can see a list of commonly used commands by typing

 help

To view information about a Windows command, use the online help:

 help commandname

For example, to view the online help for dir, enter the command:

 help dir

Alternately, to get a brief help summary for a command, enter the name of the command followed by /? -- for example, to get a help summary for the copy command, type

 copy /?

Text Editors

It's often necessary to edit a text file containing a script, program, data, or configuration information. There are many text editors available.

On Linux systems, most distributions (the organizations or companies responsible for maintaining and distributing the system) have standardized on the nano editor as the default CLI/TUI text editor (replacing the less-user-friendly vi editor). To start nano, type nano and optionally provide a filename:

 nano
 nano file

Nano provides a help display at the bottom of the screen. The carat ^ symbol indicates the control key, so the help text "^X Exit" means that you would press Ctrl-X to exit from the editor.

The current versions of Windows (Windows 10 & 11) do not provide a CLI/TUI text editor. However, you can run the GUI Notepad editor from the command line (as long as you are not accessing the Windows system remotely through a non-graphical connection):

 notepad
 notepad file