A regular expression is a pattern that describes a set of strings. Regular expressions are constructed analogously to arithmetic expressions by using various operators to combine smaller expressions.
You may noticed that network cards in new Linux have a new naming schema that will looks like eno1236558 or ens 3365777 , and you may don’t feel comfortable with that, the good news that you can get back old naming to eth0 , eth1 , … , let’s do it.
The POSIX permissions are that each file or directory has an owner, group, and other with read, write, and executable bits, but only one user and one group. ACL are an extended set of permissions.
SUID ( Set User ID ) or SGID ( Set Group ID ) upon execution are Linux access rights flags that allow users to run an executable with the permissions of the executable’s owner or group respectively and to change behaviour in directories. They are often used to allow users on a computer system to
Sticky Bit is mainly used on folders in order to avoid deletion of a folder and it’s content by other users though they having write permissions on the folder contents. If Sticky bit is enabled on a folder, the folder contents are deleted by only owner who created them and the root user.
Each file and directory has three user based permission groups: Owner/User (u)- The Owner permissions apply only the owner of the file or directory, they will not impact the actions of other users. Group (g)- The Group permissions apply only to the group that has been assigned to the file or directory, they will not
The control of users and groups is a core element of Red Hat Enterprise Linux system administration. Users can be either people (meaning accounts tied to physical users) or accounts which exist for specific applications to use. Groups are logical expressions of organization, tying users together for a common purpose. Users within a group can
Time sync became a critical part of modern system and security behaviors , ssl certificates based systems will not even work without correct timing and logging will not be helpful if it didn’t record the correct time when things happen , as all servers and PCs on your organization needs time sync , so it
Cron is a daemon that can be used to schedule the execution of recurring tasks according to a combination of the time, day of the month, month, day of the week, and week. Cron assumes that the system is on continuously. If the system is not on when a task is scheduled, it is not
The at command is used to schedule a one-time task at a specific time. batch command is used to schedule a one-time task to be executed when the systems load average drops below 0.8.