Linux basic commands

Linux basic commands :

$ who am I   –>To see from which user you have logged in

$ who           –>To see all who is logged in yet this point of time from which IP

$ w               –>More details about user related info

$ date     –> To display the date of the system

$ cal       –> To display the current month calendar

$ time             –> Calculate response time of the activity / command

$ hwclock        –> To see detailed date and time with time zone

$ ls -l      –> List files,directories with properties

$ ls         –> List files and directories

$ ls –a     –> List all hidden files and directories

$ ls –d      –> To list only directories

$ pwd        –> Print working directory

$ cd <Path of the directory>         –> Change directory

$ clear    –> To clear the screen

$ uptime        –>To see the server up time, boot time, users and load

$ uname –a     –> To verify Operating system version, kernel version and architecture

$ touch <File Name>     –>Create an empty file / Multiple empty files yet a time

$ touch –am                   –> It will change a file time to current time

$ touch –r file1 –B 30 file2  –>it will create two files with 30 seconds time difference

$ cat /dev/null > file             –>To empty the data file

$ cat > <File Name>         –>Create an single file with text

$ rm –rf <File / Directory Name>  –> Delete files/directories forcefully

$rmdir <directory>    –>Delete directories only

$ mkdir <Directory Name>   –>Create an empty directory / directories

$ mkdir –p <directory/directory/directory>  –>To create parent directories

$ cat <File Name>              –> View content of file

$ cp <Source path> <Destination path>   –> Copy the files from one path to another path

$ cp –Rv <source> <destination>            –> copy directories from source to destination

Options:

-R, -r,              #copy directories recursively

-v                     #verbose to see progress of copy job

-p                     #preserve

-f                      #forcefully

-I                     #interactive: Ask before overwriting file

$ mv <source> <destination>       –> Move files/directories

$ mv <old name> <new name>    –> Rename the file and directory

$ last               –> Check who logged in and when logged in duration

$ arch             –> To know architecture

$ reboot / init 6          –> Restart server

$ poweroff / init 0       –> To shut down the server

$ dmesg                    –> Check boot process logs

$ nsloookup <Server Address>    –> check dns resolution

$ dig <server address>      –> check dns resolution to debug

$ tree <directory>               –> It will show the tree of parent directory

$ stat <file name>               –> detailed information about file

$ wc               –> word count, character count and line count

Options:

-l          #Check line count

-c         #Character Count

-w        #Word Count

Help relate commands:

$ whatis <Command Name>  –> It will display single line description about command

$ whereis <Command Name>  –> It will provide you path of the command

$ man <command>                 –> manual page of the command

$ info <command>              –> Information about the command

$ <command> –help           –> It will gives a command options and there usage

$ apropos <keyword>          –> To know about the command use

NOTE: All commands must be small case letters