systemd – System and service manager in Linux
1.0 Introduction systemd is the newer init system used in most Linux distributions since 2015. The first widely used init system was the System V init process, sysvinit. Ubuntu introduced…
Syslog
1.0 Syslog Syslog is a protocol for conveying event notification messages. Syslog was first developed by Eric Allman for logging as a part of the Sendmail project in the 1980s.…
Find user login history – last and lastb commands in Linux
1.0 last and lastb The last command gives a chronological list of user logins in a Linux system for a period of time. The lastb commands gives a similar list…
htop command in Linux
htop is a ncurses based program for viewing processes in a Linux system. htop gives visual indications about processor, memory and swap usage.
logrotate
Linux daemons write log files. Left to itself, these log files would grow with time and take up the disk space. It is necessary to purge the log files periodically…
sar command in Linux
The sar command under Linux and Unix systems gives the system activity reports. As the system works, a record of activities is kept in certain counters in the kernel. The…
pidstat
The best way to use pidstat is to pass a list of process ids with the -p parameter. The -u option reports CPU utilization. The -l parameter displays the process…
mpstat
The mpstat command in a Linux or Unix system gives the processor related statistics. mpstat is a part of the sysstat package for performance monitoring under Linux. The mpstat command…
iostat
The iostat command is for getting the CPU and input-output devices' statistics for Linux and Unix systems. For example, $ iostat Linux 3.0.0-14-generic (hostname) Wednesday 06 June 2012 _i686_ (2…
vmstat
The vmstat command prints the system virtual memory statistics for Linux and Unix systems. vmstat prints information about system processes, memory, swap, I/O blocks, interrupts and context switches and the…