Ls stands for the List, this command is used to show the information about files and directories

Ls

It shows the list of files in your current working directory

Ls-a

-a option is used to show the list of all files including hidden files.

Ls-l

The –l option used to show the “long listing” of information about the files and directories.

Ls-al

The –al option used to show the “long listing” of information about the all files and current directories

Ls-al/ usr

The –al/usr shows the list long information about all files in the “/usr” directory

Ls –alR/usr|more

This command lists long information about all files in the “/user” directory and all sub directories and the –R options refer the ls command to give the recursive listing

Ls –ld/usr

This command lists information about the /usr  directory

This command is very useful when you want to check the permission of the directory