1.Browsing the File system 

Linux Dile Hierarchy Concepts-

 1. files and directories are organized in to a single-rooted invert tree structure.
 2. file system begins at the root directory, represented by a lone / (forward slash) character.
 3. Names are case-sensitive.
 4. Paths are delimited by /

 Some Impotent Directories- 
1. home Directories: /root, /home/username
2. user executalbes: /bin, /usr/bin, /usr/local/bin
3. system executables: /sbin, /usr/sbin, /usr/local/sbin
4. othet mountpoints: /media, /mnt
5. configuration files: /etc
6. temporary files: /tmp
7. Kernel and bootloader: /boot
8. Server data: /var, /srv
9. system information: /proc, /sys
10. shared libraries: /lib, /usr/lib, /usr/local/lib

Current working directory -

 file and directory names- 
1. names may be up to 255 characters
2. all characters are valid, except the forward-slash
3. names are case-sensitive example-: MAIL, Mail, mail, mAiL

 Absolute and Relative Path names- 
1.Absolute path names 
 >begins with forward slash
 >complete road map to file location
>can be used anytime you wish to specify a file name
 2.Relative path names 
>do not begin with a slash
 >specify location relative to your current working directory
 >can be used as a shorter way to specify a file name
 Changing Directories-
1. cd change directory
 to an absolute and relative path:
 #cd /home/johe
 #cd project/hello
 2. to a directory one level up:
 #cd ..
 3. ro your home directory
 4. to your previous working directory
 #cd -

Listing Directory contents- 
 1. lists the contents of the current directory or a specified directory 
 #ls [options] filename/directoryname
 #ls -a (include hidden files)
 #ls -l (display extra information)
 #ls -R (recurse through directories)
 #ls -ld (directory and symlink information)

Copying files and Directories-
1. cp copy files and directories
#cp [options] source_filename destination_filename
2. more than one file may be copied at a time if the destination is a directory.
#cp [options] file1 file2 file3 destination

a few common options-

 -i : (interactive) ask before overwritten a file
 -r : (recursive) recursively copy an entire directory
 -a : (archive) copies files and directory recursively

 3. if the destination is a directory the copy is placed there
 4. if the destination is file the copy overwrites the destination
 5. if the destination does not exist, the copy is renamed.

Moving and renaming files and directories- 
 1. mv move and rename files and directories
 #mv [option] source_filenamedestination
 2. more than one file may be copied at a time if the destination is a directory.
 #mv [option] file file file destination

Creating and removing files Creating and removing directory -
 1. mkdir directory name
 2. rmdir remove empty directories
 3. rm -r recursively remove directory tree

Create and Delete file-
 1. touch - create empty files or update file timestamps
 2. vi
 3. cat >filename write some data ctrl+d delete a file
 #rm filename
 5. to delete a directory
 #rm -r directory name
 6. to delete a file or directory forcefully 
 #rf -rf filename/directoryname

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