Learn Linux in 30 minutes

Artur A
Artur A
Jul 20, 2017 · 2 min read

Linux — Operating system (collection of software that manages hardware and provides an environment where application can run)

- Kernel

Linux is not UNIX derivative

1.Linux directory structure

/ Root, the top of the file system hierarchy

/bin Binaries

/etc System configuration files (config files control how OS or apps behave)

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2.The shell

Shell — is default user interface for Linux system

- command line interface

SSH — secure shell

$ — normal user

root@linuxsvr# — super user

Root is powerful. Restricteed to system admin

3. Basic linux commands

cat — content of the file

echo — content of variables

man ls — learn about command

pwd, echo

mkdir -p mon/s/a. (Create 3 directories)

Rm -rf [directory name] — recursively delete (with files inside)

vim file.txt. — create

4. Listing files

Ls -F — files

Chmod — change mode command (change permissions)

chmod u+rwx,g-x sales.txt

chmod u=rwx,g=rx sales.txt

777 for directories | 666 for files

-rw-rwxr- — User|Group|Others

5. View files

cat — view files with static content

tail -15 file.txt — displays last 15 lines (10 by default)

head -2 file.txt — displays first 2 lines (10 by default)

More file.txt

less file.txt

[enter] — 1 line down

[space] — multiple lines down

VIM/VI

i — insert at the cursor

I — insert at the beginning

x — delete character

dw — delete a word

dd — delete a line

u — undo

ctrl+R — redo

/<pattern> — start forward search (n — move to another position )

?<pattern> — start reverse search

:x — save and delete

6. Finding files and directories

find . -name s* -ls

find . -size +1

find . -type d -newer 233.txt

locate faster than find, but it’s not in real time

touch — create a file

7. Removing files

Rm file — remove file

Rm -r dir — remote the directory and its contents

8.Copying files

cp source_file destination_file

Cp src_file1 [src_fileN …] dest_dir — copy source_files to destination_directory

Cp -r source_directory destination_dir — copy src_dir recursively to destination

Diff file1 file2

9.Copying files

cp source_file destination_file

Cp src_file1 [src_fileN …] dest_dir — copy source_files to destination_directory

Cp -r source_directory destination_dir — copy src_dir recursively to destination

Diff file1 file2

10. Move

mv — move or rename files and directories

Mv file1 file2 — file 1 will be renamed

Mv source destination

mv -i source destination (interactive mode)

11. Sort

sort file1.txt

Sort -ru — reverse order

12. Wildcards

Ls *.txt

Ls a*

Ls a*t

13. Comparing

Diff

Stiff

Vim diff

14.Searching in files

Grep [string] [filename]

Grep -v [string] [filename] — invert match

Grep -i — perform a search ignoring case

Grep -ci [string] [filename] — count

File [filename] — information about file

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