Basic Linux commands for devs (flipped)

Question 1

use to get more details about the specified command and arguments that can be used with it

Answer 1

man {command}

Question 2

“Present working directory”. prints the path to the current directory

Answer 2

pwd

Question 3

used to open the specified file or internet URL

Answer 3

open {filename/url}

Question 4

list all files and folders in the current directory

Answer 4

ls

-a : adds hidden elements
-l : long format (adds more information)
-al : does both

Question 5

used to create a new folder/directory

Answer 5

mkdir {name}

can also make multiple at once by adding space separated names ex.
mkdir folder1 folder2 folder3

-p: create nested folders
ex:
mkdir -p foler1/nested

Question 6

used to create new files.

Answer 6

touch {name}

ex:
touch file.txt
touch file.txt file2.py

Question 7

used to remove empty folders

Answer 7

rmdir

ex:
rmdir folder

Question 8

used to remove empty or non-empty folders/directories/files

Answer 8

rm

ex:
rm file.txt
rm -d empty_folder
rm -r non_empty_folder
rm -r * (removes all files/folders in current directory)

note:
files will not be moved to recycle bin, it is a permanent deletion.

Question 9

used to copy files into the target folder

Answer 9

cp {file} {folder}

ex:
cp file1.txt folder

Question 10

used to move files into the target folder

Answer 10

mv {file} {folder}

ex:
mv file1.txt folder

Question 11

used to show all commands that have been typed into the Linux shell.

Answer 11

history

Question 12

used to show the difference between two files

Answer 12

diff {file1} {files2}

Question 13

used to show the first {10 lines default} of a file

Answer 13

head {filename}

ex:
head -n 15 logfile.txt
{will show the first 15 lines of logfile.txt}

Question 14

used to show the last{10 lines default} of a file

Answer 14

tail {filename}

ex:
tail -n 15 logfile.txt
{will show the last 15 lines of logfile.txt}

Question 15

used to print messages/variable values to the terminal.

Answer 15

echo {msg/$variable}

ex:
echo $username
{prints value of username}

echo *.txt
{prints all txt files in the dir to terminal}

Question 16

pings the given address to check connectivity.

Answer 16

ping {url / IP address}

note:
will run indefinitely every second until killed with {cntrl + C}

Question 17

change the current working directory.

Answer 17

cd {path}

cd ../ : moves up one level to parent directory

Question 18

print the contents of a file to the console. Can also append or overwrite file contents between two files.

Answer 18

cat {filename}

“short for concatinate”

cat >{filename}
{file contents} : will create a new file with the contents inside

cat {file1}&raquo_space; {file2.txt} : will add the contents of file1 to file2.

cat {file1} > {file2.txt} : will copy and OVERWRITE contents of file1 into file2

Question 19

Display a real-time list of processes running on the machine (similar to task manager on windows)

Answer 19

top

note: will run until you hit “q”

Question 20

used to set up shorthands of commands used frequently to avoid retyping.

Answer 20

alias {alias name}=”{command}”

Question 21

used to remove a shorthand for a command that was set up previously.

Answer 21

unalias {alias name}

Question 22

allows you to view files without opening an editor.

Answer 22

less {filename}

Question 23

create, view, and edit files in the terminal window.

Answer 23

nano {filename}
input/edit file contents -> “Cntrl + X” -> “y” to save.

Question 24

create, view, and edit files in the terminal window WITH VIM.

Answer 24

vim {filename}
input/edit file contents -> “Cntrl + X” -> “y” to save.

Question 25

search the contents of a file for a specified pattern.

Answer 25

grep {pattern} {filename}

grep -n {pattern} {filename} : print the line number where pattern is found.

grep -c {pattern} {filename} : count number of pattern occurrences.

Question 26

find the location of files that contain the given pattern in their name.

Answer 26

find {location} -name “{filename}”

ex:
find . -name “*py” : find all files and their locations that contain “py” starting at root directory.

Question 27

compress a target file/folder into a zip file

Answer 27

zip {compressed filename} {target folder/file}

Question 28

unzip a target file

Answer 28

unzip {target zip filename}

Question 29

show the disk usage of files and/or folders

Answer 29

du -h

du -h : all files/folder in working directory
du -h {file/folder} : usage of specified target

Question 30

used to retrieve files from specified URL or IP address

Answer 30

curl {address} : this will fetch contents of the file without saving them

curl -o {new filename} {address} : will fetch contents and save them into a new file.

Question 31

change the owner or user group associated with a file/directory

Answer 31

sudo chown {username} {target file/folder}

sudo chown :everyone {target file/folder} : will change the user group associated to everyone.

sudo chown {username}:{group name} {target file/folder} : will change both username and user group.

Question 32

used to modify the permissions or file modes associated with different files or directories.

Answer 32

chmod {user/group/other} {operation}{permissions}

{user/group/other} u=user, g=group, o=all others.
{operation} +(add permission) -(remove permissions) =(set permissions to)