Week 2 + 3 Flashcards
What do the commands below do?
tilda (~) command?
whoamii command?
pwd command?
cd command?
tilda(~) goes to the home directory
whoami checks who the user is
pwd checks the current working directory(where u are)
cd command changes directory listed after cd
What are Paths?
Types of Paths?
List of directories separated by /.
example: /home/tenzing/desktop
Types: Absolute(starts with /), and Relative
Differences with Absolute and Relative paths?
Absolute: starts with / root directory
Relative: starts at current directory. use .. to go back a directory or ../../
What does ls -a command do?
what does ls -l command do?
Shows all hidden files and folders, hidden folders will have a . in front
Gives a long list with detailed info.
1st Column: File type and access
permissions
* 2nd Column: # of HardLinks to the
File
* 3rd Column: Owner and the
creator of the file
* 4th Column: Group of the owner
In the ls -l command
The first character on each line indicates the type.
List the types:
d (directory)
- (regui]lar file)
l (symbolic link)
s (socket)
p (pipe)
b (block file)
c (character file)
drwxr-xr-x
define this
d(type)
rwx(read-write-execute for owner)
xr(perms for group)
x(perms for others)
r = read
x = execute
w = write
What does -h command do?
And describe human-readable format?
when file size too big makes it easier to read. M - megabytes, G - Gigabytes, T- Terabytes.
What are different ways to sort with ls command?
ls -r (recursive, sort backwards)
ls -s (sort by file size)
ls -t (sort by time)
How to use ls to get a detailed timestamp?
ls –full-time
How to get to the manual page on how to use glob?
man 7 glob
What does the asterisk(*) do? and uses?
- represents any name
d - name that ends with d
a - name that starts with a
c - name that contains c
a*c - name that starts w/ a and ends w/ c
- represents any name
What does the ? character do?
??? - names that contain 3 characters
d.??? - name that starts with d. then contains any 3 characters
What does the square brackets do
[ ]?
[abc]d - begins with either a, b, or c and ends with d.
[a-zA-Z][0-9] - begins with any letter lower or uppercase and ends with any number from 0-9
What does [!] do?
[!abc]d – this is a name that does NOT begin with either character ‘a’
or ‘b’ or ‘c’ and ends with character ‘d’
What do the curly brackets do?
Curly brackets {} are used to specify terms that are separated by commas and each term must be a name or a wildcard.
Same as IN (value1, value2) in DBAS
How to create text files?
touch newfile.txt
or
cat > newfile.txt
content
content
CTRL-D to save
How to create directory?
and
How to create 3 directories at once? named ‘a’, ‘b’, ‘c’
mkdir directoryname
mkdir a b c
Create a two parents(o and s)
and s has two children
mkdir -p o/p/q/r s/{sub1,sub2}
How to remove directories and files?
rmdir to remove directory
rm filename or
rm -r filename to force delete
How to copy and move files and directories?
copy files:
cp filename end location
copy directory:
cp -r directoryname endlocation
move files:
mv filename endlocation
Use -n for no clobber, to prevent cp and mv commands from overwriting content at the destination
How to rename files or directories?
rename directory ‘a’ to ‘aaa’ and move ‘aaa’ to ‘b’
mv directory newname
mv a b/aaa
Types of text editors?
nano and vim
Explain the difference between single hypen(-l) and double hyphen?
Single hypen options are for short form (-h), while double hypen are for full words (–human-readable).
How to check for history?
history command
Create a variable called greet and assign it a value of Hello. Then Display it.
greet=Hello
echo $greet
Export the variable greet as an environment variable. Then unset it.
export greet
env | grep greet
unset greet
What are the 4 types of commands
Internal - part of the shell(cd)
External - require executable files to run (which command)
type -a echo
Aliases - short name given to long commands
Functions - Complex structures that can be used to create new commands or change behaviour of existing commands
What is root user
Root is a superuser account.
Recommended that you use sudo instead as a home user.
The CLI is a very powerful and fast interface that allows users ______ ________ _______ _________ ______ _______ _________.
The CLI is a very powerful and fast interface that allows users to complete various tasks
by issuing commands.
Once a user has entered a command, the terminal then accepts what the
user has typed and passes it to _ ___.
Once a user has entered a command, the terminal then accepts what the
user has typed and passes it to a shell.
A shell is an application that allows users to use the services of an operating
system
It is named a shell because it ___________________________________.
_____ is the most commonly used shell in Linux.
A shell is an application that allows users to use the services of an operating
system
It is named a shell because it is the outermost layer around the operating system.
Bash is the most commonly used shell in Linux.
breakdown the components:
tenzing@comp:~$
tenzing@comp:~$
tenzing: Username
comp: System name
~: current directory(~ means home)
Two types of variables in Bash shell?
Local variables - store values, perform calculations, etc.
Environment variables - used to control the Linux run time environment
Format for making a local variable?
How to check the value of a variable named “sum”
$ var=Hello
var(variable name)=Hello(value)
echo $sum
There are many environment variables. For example: _____, _____, and ________ variables.
There are many environment variables. For example: PATH, HOME, and HISTSIZE variables.
The ___ command outputs a list of the environment variables.
The _______ command is used to turn a local variable into an environment variable.
Variables can be removed using the unset command: _____ ___
The env command outputs a list of the environment variables.
The export command is used to turn a local variable into an environment variable.
Variables can be removed using the unset command: unset var
Internet commands are the shell built-in commands.
Two Internal commands are ____ and ______
Two Internal commands are cd and echo
you can use the type command to check.
External commands can be executed by typing _____ ______ __________ _______ _____ ________ __________.
External commands can be executed by typing the complete path to the executable file for that command.
the type command displays the location of external commands.
