Linux full Course ~ IT Infosoft

Linux root Directories:

Linux File Systems:

bin boot dev etc home lib lib32 lib64 libx32 lost+found media mnt opt proc root run sbin snap srv sys tmp usr var

/bin: Essential binary files and commands required for system boot and recovery.

/boot: Boot loader files, kernel images, and configuration for booting the system.

/dev: Device files representing hardware devices or pseudo-devices.

/etc: System-wide configuration files and scripts.

/home: Home directories for user accounts.

/lib, /lib32, /lib64, /libx32: Libraries required for running programs.

/lost+found: A directory where orphaned files go after a file system check.

/media: Mount points for removable media like USB drives and CDs.

/mnt: Mount points for temporarily mounted file systems.

/opt: Optional software packages and their associated files.

/proc: Virtual file system providing information about running processes.

/root: Home directory for the root user.

/run: System runtime data, including PID files and sockets.

/sbin: System binaries, usually used for system maintenance tasks.

/snap: Snap packages, a package format for application distribution.

/srv: Data for services provided by the system.

/sys: Virtual file system exposing kernel and hardware information.

/tmp: Temporary files and directories for system and user applications.

/usr: Secondary hierarchy containing user binaries, libraries, and data.

/var: Variable data, such as logs, spool files, and temporary data.

These directories collectively organize the file system in Linux, helping to maintain a structured and organized environment for system files and user data.

&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

Linux Basic Commands:

-----------------------

Reference:

- https://www.hostinger.in/tutorials/linux-commands

- https://www.guru99.com/unix-linux-tutorial.html

- https://www.tutorialspoint.com/unix/index.htm

3. Shell

pwd

Shell/Terminal

cat

mkdir

rmdir

touch

----

AWK

how do you print a particular line number using awk.

----

Pipe

apt-get

Process

push a process in background mode

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Navigation: Linux Commands

Basic Commands:

pwd: Print the current working directory.
ls: List files and directories in the current directory.
ls -l: List in long format (with details).
ls -a: List hidden files.
cd Change directory.
cd : Move up one directory.
cd. Move to the home directory.
cd / Move to the root directory.

File and Directory Operations:

mkdir Create a new directory.
rmdir Remove an empty directory.
touch Create an empty file.
rm Remove a file.
rm -r Remove a directory and its contents (use with caution).
rm -rf Remove a files directories and its contents forcefully.
cp Copy files or directories.
mv Move or rename files or directories.

Viewing and Editing Files or File and Text Manipulation:

cat Display the contents of a file.
more View a file one screen at a time.
less. View a file one screen at a time.
head Display the first few lines of a file.
tail Display the last few lines of a file.
nan, vim Text editors.
vim Open a text editor to edit a file.
grep Search text using patterns.
find Search for files and directories.
wc Count words, lines, or characters in a file.
To save changes in vim, press Esc and :wq

Redirection and Pipes:

>, >>. Redirect output to a file.
< Read input from a file.
| Pipe output of one command as input to another.

Process Management:

ps: List currently running processes.
ps -ef List processes.
ps aux List all processes in detailed format.
kill. Terminate processes.
kill [p_id] Terminate a process by its ID.
killall [process_name]: Terminate all processes with a given name.
top Monitor system processes in real-time.
htop Monitor system processes in real-time.
jobs, fg/bg Manage background processes.

File System Information:

uname -a: Display system information.
df -h: Show disk space usage.
free -m: Display memory usage.
df Disk space usage.
du Disk space usage.
free, top. Memory usage.
lscpu CPU information.
nproc CPU information.
lsblk List block devices and manage disk partitions.
fdisk: List block devices and manage disk partitions.
mount Mount file systems.
umount Unmount file systems.
df and du Disk space usage and folder size.

Users and File Permissions:

who: Show who is logged in.
whoami Display the current user.
useradd Create a new user.
userdel: Delete users.
passwd Change a user's password.
chmod Change file permissions.
chown Change file ownership.
sudo, su. Execute commands with superuser privileges.

Package Management (Ubuntu/Debian):

sudo apt update: Update package lists.
sudo apt upgrade: Upgrade installed packages.
sudo apt install Install a package.
sudo apt remove Remove a package.
dpkg -i [package.deb]: Install a .deb package.
apt-get and yum Install, update, and remove packages.
apt (Debian/Ubuntu), yum (Red Hat/CentOS): Package management.
dpkg (Debian/Ubuntu), rpm (Red Hat/CentOS): Package management at a lower level.

Networking:

ifconfig, ip Show network interfaces and their Network configuration.
ping Send ICMP echo requests to a host.
traceroute Network troubleshooting.
netstat Display Network Connections and Routing tables.
ss, lsof Network and socket information.
ssh Secure shell and secure copy for remote connections and file transfer.
scp Secure shell and secure copy for remote connections and file transfer.
nproc To check the number of vCPU Core.

Archives and Compression:

tar -czvf Create a compressed tarball.
tar -xzvf Extract files from a tarball.
zip Create a ZIP archive.
unzip Extract files from a ZIP archive.
tar Archive and compression utility.
gzip Compress files with Gzip.
gunzip Decompress files with Gzip.

Remember to use man [command] to access the manual pages and learn more about each command's options and usage. Linux offers a vast array of commands and utilities, so this cheatsheet covers only the basics.

System Startup and Services:

systemctl. Manage system services.
service (SysVinit): Control system services (older systems).
chkconfig Configure system services (older systems), (Red Hat/CentOS).

Miscellaneous:

date Display or set the system date.
time Display the system time.
history Command history.
alias Create shortcuts for commands.

Shell Scripting:

#!/bin/bash: Shebang line in shell scripts.
Variables, conditionals, loops, and functions in shell scripts.
chmod +x script.sh: Make a script executable.

Linux Process Management with nohup, nice, bg, fg, jobs, kill Commands

$ jobs Will show active jobs.

$ bg Resume jobs to the background.

$ fg Resume jobs to the foreground.

$ nice nice -n -10 process

$ nohup It will run the tasks or jobs even after closed terminal

$ fg %job_id Resume a specific jobs

$ bg %job_id Resume a specific jobs

nice value Niceness scale goes from -20 to 19. The lower the no. more priority that task gets.

Process priority = nice

eg.

$ nice - 10 process

$ Distros/echo.sh

$ ctrl + Z

$ ps -ef | grep echo

$ ps -l pid To check the nice value

$ kill -9 pid

$ ps -ef | grep echo

$ jobs

$ nice -n -10 /Distros/echo.sh

$ Ctrl + Z

$ ps -ef | grep echo

$ ps -l pid Now again see the nice value is been changed from 0 to -10.

Open two terminal parallels:

$ nohup

Once you close the terminal jobs get closed automatically that’s why using which we can continue after terminal get closed.

$ nohup ./echo.sh &

$ ps -ef | grep echo

Now close the terminal and open again you will see the jobs are still running

$ ls -ltr nohup.out

$ less nohup.out. See the logs or your task output.

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

Personal

pwd — To check Present working directory

cd — To change working directory

ls — long list to see the files and directories.

ls -l — long list to see the all files and directory details.

ls | nl — To check the files with number of lines.

cat > filename — to create file with data.

ctrl +D — Exit from file

сp — To copy the file on directory

mv — to move files or directories and "rename also"

mkdir — to create directories.

mkdir -p — to create multiple parent directories.

rmdir — to remove empty directory

reset — reset search history

rm -r — To delete only directory

rm -rf — to remove file or directory forcefully.

touch — to create single on multiple empty files

rm -f — remove file without warning.

rm -i file — Before deleting the file it will ask your permission.

rm -f file — Delete forcefully.

rm -r file — Delete file & directory recursively.

mkdir -m <dir_name — To create directory with full permissions.

find . - name < filename> — To find the file whether it is present or not.

find . -name dep*.log — Find the files present in directory.

find . -name “*.log" — To find all files ending with .log

grep "Error" build.log — To find the String in file.

grep - i "Error" build.log — To see the all string which is starting from small or capital

grep - in "error" ‹filename› — To see the string in line number.

man grep — To check more commands of grep.

grep error -in build.log — to see string with line no.

grep error - A2 - in < file name» — To see the 2 lines after string error.

grep error - A2 - B2 - in < filename> — to see the 2 lines before 4 after string.

grep error -inc ‹filenames — To see the count of string or files.

sudo su — switch user do as root user.

whoami

sudo su raghunath — to be an admin.

apt-get install git

apt-get update -y

lsb-release - a — To cheek linux details.

sudo apt -get install tree - y

yum install or update — date (for CentoS, RHEL)

/ — slash means root directory

su root — switch user as root

df . — it will show the current directory space in kb

df -h . — To see overall disk space in GB

df -h — To see the space of all file & directory

du <filenames> — To see file uses details

du -h < filename> — To see the space details in MB, single file or directory

du -sh <dir-name> — see the details in MB

vim /etc/sudoers — to change permission

:q! — Exit forcefully

head <f.name> — To see top 10 lines if contents

head - 5 <filename> — To see top 5 lines

tail <filename> — To see bottom 10 lines file contents

tail - 2 < f.name> — see last 2 lines

head - 10 <filename> | tail - 2 < filename> To see top 10 and last 2 lines of file contents.

cat < filename> —To see file content

cat -n < f.name> — To see content in lines

cat >> filename — To add content in same files

cat -n < filename> | grep error — To see the string in line number.

cat file1 file2 > file.txt — To store or merge file1 file2’s data in file.txt

cat logs.yaml | grep -i hostname — To check the exact words in files

cat logs.yaml | grep -i "hostname:" — To check the exact words in files

grep -iv error <filename> — To see file contents without string like inverts

egrep -i "Error | Exception" < filename> — To see the multiple strings.

egrep "error | Error" <filename> — To see the multiple strings.

grep - iw " Error Exception" < filename› — to see exact matching word or string

cat build.log | grep -i error | grep exception — to see both string together in all lines

clear — clear the screen

diff <filename> < filename2> — To cheek the diff. b/w two files

vimdiff <filename> < filename2> — To see the file contents in two different windows

ctrl + ww — to jump another window

diff -c

diff -u

diff -i

tar -xvf <filename> — to extract the tar file

tar -cvf filename.tar <filename> — to create tar file

ls -l

ls -a

ls -al

ls -latr

chmod 777 build.log — To change file permission.

sudo chown sally <filename> — It will change file ownership.

chown Raghu:Raghu build.log — To change the file ownership.

sudo chown A:A build.log — To change the file ownership with group.

mkdir . — To create hidden directory.

touch . — To create hidden empty file.

rm -rf * — To remove everything in current directory.

ps -ef | grep firefox — To see Firefox process and it’s details.

jobs — To check the process which is running in background mode.

ps -ef — In Linux, ps -ef is a command that displays information about running processes on the system.

kill 2124 — To stop forcefully.

kill -9 2124 — it will kill the process forcefully.

deploy.sh

— it is a script which will run for 30 minutes, if wants to stop then press ctrl + c.

sleep 100 & — To run script in background.

fg1 — To see background mode.

sleep 1000 &

fg3 — To bring it back.

ctrl c or x — Exit from it.

ping google.com — To check the mission which is working in Linux.

wget <url> — To downloads.

wget -P /home/user/directory <url> — To download in a particular directory.

ssh 172.17.0.2 — To connect mission with ip address.

uname -a — To check user_name with linux details.

hostname —

top — To see the Memory and CPU Utilization.

history

man —help — To see more commands related man.

echo hello

zip file_name.zip <file_name> — To zip a file.

uzip <file_name>

vim /etc/hosts — To copy ip address and paste as another hosts

:q! — Exit forcefully without any changes.

vim /etc/hostname — To give another name then logout & login again.

echo $SHELL — To see /bin/bash.

a = 10

echo $ a

sudo useradd -md /home/Raghu -s /bin/bash Raghu

id raghu

sudo passwd Raghu

sudo userdel Raghu

vim /etc/sudoers — To add permissions.

$$$$ Search vimcheatsheet, gitcheatsheet, mavencheatsheet.

vim.vimrc — To set numbers.

vim - O <filename> <filename2>

— it will open on two terminal with same screen.

evince filename.pdf — To open pdf files in linux terminal.

cd .. — Back to previous directory.

ls -lt — shorted last modified time.

ls -ltr — To see reverse output.

ls -R — Lists all the files in the subdirectories.

ls -lh — Show the file size such as MB, GB, TB.

tac file.txt — see the data in reverse order.

Shell/Terminal

seq 10 — To print number from 1 to 10.

ls /etc/init.d — it will bring up a list of currently running services.

sudo systemctl restart <service_name>

— To restart running & stopped services.

cp build.txt pom.txt

— To copy data from build.txt to pom.txt but the data is presented in pom.txt will be replaced from file.txt.

touch /home/Raghunath/Documents/web.xml — Create file inside particular directory.

sudo apt-get install locate

locate -i <string_name> — Locate string name using locate command.

grep -in “yes” hello.txt — To check file that contain “Yes” words.

apt list —upgradable — To check upgraded packages.

stat <filename> — To see time stamp like access time and modify time.

$ touch -a <file_name> — To change access time.

$ touch -m <file_name> — To change modify time.

$ nano file1 — To create file and write data into it.

$ crtl + X, Y — Exit from nano and save with $Y.

$ hostname -i — Check ip address with machine details.

$ cat /etc/os-release

$ chmod u=r, g=rwx, o=x file_name

$ chmod 777 <dir_name-file_name>

$ chmod u+w, g-w, o+r

$ chgrp <g-name> <new-g_name> — To change group name.

$ cd ~ — come to home directory directly.

$ sudo !! — it will run previous command with sudo.

$ history

$ ! 220 — it will execute command automatically.

$$———————————————————————————$$

Thanks 🙏

About Admin MC3

This is dummy text. It is not meant to be read. Accordingly, it is difficult to figure out when to end it. But then, this is dummy text. It is not meant to be read. Period.

Linux full Course

About Admin MC3

Related Post