Cloud Linux

for some basics refer Basics of Linux

2 types

1. Debian (Kali, Ubuntu) Packages end with : .deb
2. RPM (Oracle Linux, Centos,REHEL) Packages end with : .rpm

Commands :

cp -r (target_directory_name) (Final_directory_name)   # Copy Directories
cat > /dev/null > file_which_needs_to_be_cleared.txt   # Clears file content
ls | wc -l                                             # Counting
passwd (username)                                      # Change password
 
scp file.txt user@remote_host:/path/filename.txt       # Moving files
                                                       # from Local to remote
 
scp user@remote_host:/path/file.txt /dest/filename.txt # Moving files
                                                       # from remote to local

Mounting Storage :

To mount a storage permanently Edit the /etc/fstab file and add these lines : /dev/sdb1 /mnt/mydrive ext4 defaults 0 0 (For Local) server:/path /mnt/mydrive nfs defaults 0 0 (for NFS) and then do sudo mount -a

Users & Groups :

groupadd (group name)
useradd (username)
id (username)                        # Check about the user
useradd -G (groupname) (username)    # Adds that user in that group
sudo chown (user):(group) /path/to/directory   # Adds a group/user for the directory to be accessed you can later change that perm with chmod (leave blank if no user is there ex : chown :G1 /file) 

File Permisions :

Example : drwxrwxrwx

Green - File Type Pink - Owner Yellow - groups Blue - Others

Changing permissions :

chmod (user)(+or-)(Permission) (filename)
Ex : chmod o+x filename.txt
	 chmod g+w filnema.txt
 
# Or follow numeric configuration of :
r,w and x = 7
r and w = 5
etc..
chmod 770 filename.txt

Archiving :

zip -r directory_name.zip directory_location
unzip directory_name.zip

Files :

/etc/passwd                              - user IDs 
/etc/shadow                              - user Password
                         #User ID of root is 1

VIM :

:se nu           # Displays the Line numbers
:wq              # Saves and quits
Shift + G        # Goes to last line
g + g            # goes to first Line
/word            # Searches that word
:%s/text1/text2  # Replaces text1 with text2

be familiar with grep commands

> command ovewrite existing file or creates new file
>> dosen’t overwrite