systemd – System and service manager in Linux

systemd is the system and service manager for Linux based systems. systemd concepts, configuration directives and commands are explained.

Syslog

Syslog is a protocol for conveying event notification messages. Syslog concepts and calls for logging messages are explained.

last and lastb commands print the user login history. last prints the previous logged in users and lastb shows the failed login attempts.

sed is a stream editor that applies the commands one by one on each line of input and writes the resulting lines on the standard output.

Shell is the command line user interface to a UNIX-like system. bash is the default shell under Linux.

htop is a ncurses based program for viewing processes in a Linux system. htop gives information about processor, memory and swap usage.

logrotate is for rotation of log files daily, weekly, monthly, or when a log file becomes bigger than the predefined limit.

The sar command gives information about CPU, I/O, paging, devices, memory, swap space, network, run queue, interrupts and power management.

The pidstat command gives the CPU utilization, I/O statistics, page faults and memory utilization for processes and threads in Linux systems.

The mpstat command in a Linux system gives the CPU utilization report and the hardware and software interrupts per second for processors.