| command that displays kernel buffer ring | dmesg | less |
| command that displays kernel buffer ring | dmesg | less |
| command that displays kernel buffer ring | dmesg | less |
| command that displays kernel buffer ring | dmesg | less |
| What are deamons? | They are utility programs that run silently in the background to monitor and take care of certain subsystems to ensure that the operating system runs properly. |
| Which suffix denotes deamon? | d example: ssshd |
| What are controlling scrpits? | UNIX systems use scripts to control “daemons” which provide “services” (for example your sound output) to run a UNIX system. |
| What is runlevel? | A runlevel can be thought of as the state your system enters like if a system is in a single-user mode it will have a runlevel 1 while if the system is in a multi-user mode it will have a runlevel 5. |
| command used for changing current runlevel | performed by root
init 0 -system shutdown
init 6 -system reboot |
| What is System V? | One of the first UNIX version introduced by AT&T |
| command for opening ttys | getty or agetty |
| What about runlevels on BSD systems? | The idea of runlevels is discarded on BSD |
| What is Systemd? | It is windows inspired replacement for desktop-oriented linux systems |
| How are deamons called under Systemd? | services |
| What is Systemd target? | Systemd targets are different states that your system can boot into, comparable to System V runlevels |
| Command used to control and manage systemd utitilites | systemctl |
| Can most UNIX deamons be started as systemd services? | Yes, they can
Moreover standard deamons can be installed and double services |
| What is Cron? | Cron is UNIX deamon for executing commands periodcially on certain times and dates |
| What is crontab file? | It contains instruction for a cron deamon
Once a minuite cron checks crontab files and executes all commands that are scheduled |
| Are users able to define their own crontabs? | Yes |
| What is syslog deamon? | It is deamon to which kernel and other deamons send messsages containing date, time etc
Syslog messages are redirected to terminal or to remote syslog instance |
| command used to interact with syslog | logger |
| What is the difference between Syslog and syslog-ng? | Syslog is a protocol
syslog-ng is an implementation |
| What are logs? | Linux logs provide a timeline of events for the Linux operating system, applications and system and are a valuable troubleshooting tool when you encounter issues. When issues arise, analyzing log files is the first thing an administrator needs to do. |
| What is logrotate? | useful tool for log managements which is initaied once a day by a cron |
| command that displays kernel buffer ring | dmesg | less |
