Tag: Commands

Create a file in Linux

December 7, 2021 / sandeeppote

Create a file with touch command

To create a new file, use touch command followed by the name of the file-

This should create a empty file.

touch thirdfile.txt

To create multiple files using touch command-

touch thirdfile-1.txt thirdfile-2.txt

Create a file with cat command

To create a new file with cat command use redirection operator followd by file name.

This will allow to add content to the file

cat > fourthfile.txt

Cratea a file using echo command

To create a new file using echo command use redirection operator followed by file name will create empty file or add content before redirection operator to add content while creating a file.

echo "This is fifth file." > fifthfile.txt

Create a empty file with echo command

echo > sixthfile.txt

Linux File Types

December 5, 2021 / sandeeppote

Everything in Linux is file

There are following type of files-

Regular files – Images/scripts/configuration and Data files

Directory – Type of files which saves other files and directories

Special files – have other types

Character Files – Represent devices – like Mouse and keyboards
Block Files – Represent block devices that writes data in chunk to the devices like HDD and RAM
Links – Hard links and Soft Links
Socket Files – enables the commnuication between 2 process
Named Pipes – passes data from one process to another

Use file command to get the file type-

file <<filename>>

Use ls -ld command to get the file type-

ls -ld firstfile.txt

First character represents the file type

Identifier	File Type
d	Directory
–	Regular File
c	Character Device
l	Lin
s	Socket File
p	Pipe
b	Block Device

Filesystem Hierarchy

/- Root Partition

/opt – any third party program should be put in this directory

/mnt- mounts the file system from external network temporary to this folder

/tmp- copy any temporary files to this location

/media – copy any media files in this folder

/dev – contains the file character device file like external devices like mouse and keyboard

/bin – basic programs and binaries are located in this directory

/etc – configuration files

/lib and /lib64 – contains shared libraries

/usr – user related data reside in this folder

/var – system writes data such as logs

Linux Runlevels

December 5, 2021 / sandeeppote

A runlevel is a categorization number that determines what services are started and
what services are stopped

Runlevel #	Name	Description
0	Halt	All services are shut down and the server is stopped
1	Single User Mode	The root account is automatically logged in to the server and other users cannot log in to the server
2	Multiuser Mode	Users can log in to the server through CLI and network service are not started
3	Extended Multiuser Mode	Users can log in to the server through CLI and network service are started
4	User Defined	User can cusomize the runlevel
5	Graphical Mode	User can log in through CLI and GUI with network services started
6	Reboot	The server is rebooted

Check the current runlevel use following command-

runlevel

To see the default target

systemctl get-default

To change the default target use following command

systemctl set-default multi-user.target

LINUX Managing Accounts – commands

June 19, 2021 / sandeeppote

All the commands for user account should run from root(i.e. supper user). Use SUDO command to get the privilege’s

See the current user details use id command

Check the name of the current user, use whoami command

See users currently logged in to the system- use who command

See the history of the users logged in to the system with the details system was rebooted, use last command-

Managing User

Adding a new user, use useradd command

Check the newly created user, use grep command. User is created in /etc/passwd-

Following is the format of the user details in /etc/passwd-

shuser2:x:10001:10002:User with custom options:/home/shuser2:/bin/bash

USERNAME:PASSWORD:UID:GID:GECOS:HOMEDIR:SHELL

To set the password for newly created user, use passwd command

If the re-typed user password is wrong error is displayed

To change the current users password use passwd command without user name

Options whilst creating a user

Options	Description
-c	set custom comments
-d	set custom home directory
-e	set expiry date
-g	set specific GID
-G	create user with multiple secondary group
-s	specify login shells
-u	specify UID