Basic Linux Dig commands

# dig google.com
# dig google.com +short

MX Record

# dig google.com MX

SOA Record for Domain

# dig google.com SOA

TTL

# dig google.com TTL

Get only Answers

# dig google.com +nocomments +noquestion +noauthority +noadditional +nostats

Get all DNS Records Types

# dig google.com ANY +noall +answer

DNS Reverse Look-up

dig -x 216.58.206.110 +short

Multiple DNS Records

# dig yahoo.com mx +noall +answer redhat.com ns +noall +answer

Create $HOME/.digrc to configure

Useful Linux CLI commands

hostname -I
[root@ftp ~]# groups
[root@ftp ~]# groups root
[root@ftp ~]# grep root /etc/group

Symbolic Links

Hard Link

ln /path/to/file /path/to/hardlink

Soft Link

ln -s /path/to/file /path/to/link

To Prevent Soft Link Overwrite

ln -s -b /path/to/file /path/to/link

List all symbolic links

ls -lt

Unlink a file

unlink linkfile
grep -r SSLCertificateFile /etc/httpd
httpd -S
openssl x509 -in server.crt -noout -subject

All users:

$ getent passwd

All groups:

$ getent group

All groups with a specific user:

$ getent group | grep user

Delete user

userdel user's username

Delete including users home directory

userdel -r user's username

SSH : Change Owner of files and folders

Change Owner of All files within a Folder

Here is how to change Owner of Files and Folders in SSH as a Bulk

  • Login to SSH
  • Run chown -R user:usergroup /location/of/the/folder/*
$ chown -R user:usergroup /location/of/the/folder/*

Change Owner of one file

$ chown user:usergroup /location/of/the/folder/file-name.php

Find the list of files under an Owner

$ find /location/of/the/folder/ -user USERNAME