sysadmin

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 the Upstart init system with Ubuntu 6.10 in 2006. Ubuntu fully migrated to systemd with Ubuntu 15.04 in 2015. Indeed, we can see that /sbin/init …

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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. It soon became a de-facto standard for logging on Unix-like systems. Syslog was formally specified in RFC 3164 in 2001 as “The BSD syslog Protocol” …

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sed command in Linux

1.0 sed sed is a stream editor that accepts a list of commands and input file names. It applies the commands one by one on each line of input and writes the resulting lines on the standard output. The commands are separated by newlines. 2.0 sed Command syntax sed [OPTIONS] ‘list-of-sed-commands’ filenames … sed is …

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An Introduction to Shell in GNU-Linux

1.0 SHELL A shell provides a user interface to a computer system. There are two types of shells, the command line interface (CLI) and the graphical user interface (GUI). In this tutorial, we describe the command line interface shell only and refer to it simply as shell. A CLI shell is a programmable command interpreter …

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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 so that the disk space is conserved and is available for smooth running of the system. logrotate is a utility for rotation, compression, removal and …

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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 sar command gives statistics regarding the CPU, I/O, paging, devices, memory, swap space, network, run queue length and load average, interrupts and power management. At …

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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 command name and its arguments. And we can optionally put time interval in seconds for the interval between reports and again, optionally, a count for …

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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 gives the CPU utilization report and the hardware and software interrupts per second for each processor. By default, the CPU utilization report is printed. For …

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