This article is written like a manual or guide.(July 2023) |
Stable release | sysstat 12.1.1 [1] / October 13, 2018 |
---|---|
Preview release | sysstat 11.7.4 / June 1, 2018 [2] |
Repository | github |
Written in | C |
Operating system | AIX, Linux, Solaris, HP-UX |
Type | System reporting |
Website | sebastien |
System Activity Report (sar
) is a Unix System V-derived system monitor command used to report on various system loads, including CPU activity, memory/paging, interrupts, device load, network and swap space utilization. Sar uses /proc
filesystem for gathering information. [3]
Sar was originally developed for the Unix System V operating system; it is available in AIX, HP-UX, Solaris and other System V based operating systems but it is not available for macOS or FreeBSD. Prior to 2013 there was a bsdsar
tool, but it is now deprecated. [4]
Most Linux distributions provide sar
utility through the sysstat
package.
sar [-flags] [ -e time ] [ -f filename ] [-i sec ] [ -s time ]
[user@localhost]$ sar# Displays current CPU activity.
Additional to sar
command, Linux sysstat package in Debian, [5] RedHat Enterprise Linux and SuSE provides additional reporting tools:
sar
, supporting the same flags as sar
command which write a daily report in the /var/log/sa directory. – Linux Administration and Privileged Commands Manual sar
but can write its data in different formats (CSV, XML, etc.). This is useful to load performance data into a database, or import them in a spreadsheet to make graphs.A man page is a form of software documentation usually found on a Unix or Unix-like operating system. Topics covered include computer programs, formal standards and conventions, and even abstract concepts. A user may invoke a man page by issuing the man
command.
In UNIX computing, the system load is a measure of the amount of computational work that a computer system performs. The load average represents the average system load over a period of time. It conventionally appears in the form of three numbers which represent the system load during the last one-, five-, and fifteen-minute periods.
The Filesystem Hierarchy Standard (FHS) is a reference describing the conventions used for the layout of Unix-like systems. It has been made popular by its use in Linux distributions, but it is used by other Unix-like systems as well. It is maintained by the Linux Foundation. The latest version is 3.0, released on 3 June 2015.
tmpfs is a temporary file storage paradigm implemented in many Unix-like operating systems. It is intended to appear as a mounted file system, but data is stored in volatile memory instead of a persistent storage device. A similar construction is a RAM disk, which appears as a virtual disk drive and hosts a disk file system.
The archiver, also known simply as ar, is a Unix utility that maintains groups of files as a single archive file. Today, ar
is generally used only to create and update static library files that the link editor or linker uses and for generating .deb packages for the Debian family; it can be used to create archives for any purpose, but has been largely replaced by tar
for purposes other than static libraries. An implementation of ar
is included as one of the GNU Binutils.
fstab is a system file commonly found in the directory /etc
on Unix and Unix-like computer systems. In Linux, it is part of the util-linux package. The fstab file typically lists all available disk partitions and other types of file systems and data sources that may not necessarily be disk-based, and indicates how they are to be initialized or otherwise integrated into the larger file system structure.
stat is a Unix system call that returns file attributes about an inode. The semantics of stat vary between operating systems. As an example, Unix command ls uses this system call to retrieve information on files that includes:
mv
is a Unix command that moves one or more files or directories from one place to another. If both filenames are on the same filesystem, this results in a simple file rename; otherwise the file content is copied to the new location and the old file is removed. Using mv
requires the user to have write permission for the directories the file will move between. This is because mv
changes the content of both directories involved in the move. When using the mv
command on files located on the same filesystem, the file's timestamp is not updated.
The file
command is a standard program of Unix and Unix-like operating systems for recognizing the type of data contained in a computer file.
The proc filesystem (procfs) is a special filesystem in Unix-like operating systems that presents information about processes and other system information in a hierarchical file-like structure, providing a more convenient and standardized method for dynamically accessing process data held in the kernel than traditional tracing methods or direct access to kernel memory. Typically, it is mapped to a mount point named /proc at boot time. The proc file system acts as an interface to internal data structures about running processes in the kernel. In Linux, it can also be used to obtain information about the kernel and to change certain kernel parameters at runtime (sysctl).
File attributes are a type of meta-data that describe and may modify how files and/or directories in a filesystem behave. Typical file attributes may, for example, indicate or specify whether a file is visible, modifiable, compressed, or encrypted. The availability of most file attributes depends on support by the underlying filesystem where attribute data must be stored along with other control structures. Each attribute can have one of two states: set and cleared. Attributes are considered distinct from other metadata, such as dates and times, filename extensions or file system permissions. In addition to files, folders, volumes and other file system objects may have attributes.
In computing, the sticky bit is a user ownership access right flag that can be assigned to files and directories on Unix-like systems.
tail is a program available on Unix, Unix-like systems, FreeDOS and MSX-DOS used to display the tail end of a text file or piped data.
In computing, a dynamic linker is the part of an operating system that loads and links the shared libraries needed by an executable when it is executed, by copying the content of libraries from persistent storage to RAM, filling jump tables and relocating pointers. The specific operating system and executable format determine how the dynamic linker functions and how it is implemented.
vmstat is a computer system monitoring tool that collects and displays summary information about operating system memory, processes, interrupts, paging and block I/O. Users of vmstat
can specify a sampling interval which permits observing system activity in near-real time.
iostat is a computer system monitor tool used to collect and show operating system storage input and output statistics. It is often used to identify performance issues with storage devices, including local disks, or remote disks accessed over network file systems such as NFS. It can also be used to provide information about terminal (TTY) input and output, and also includes some basic CPU information.
In Unix-like operating systems, a loop device, vnd, or lofi is a pseudo-device that makes a computer file accessible as a block device.
chattr is the command in Linux that allows a user to set certain attributes of a file. lsattr is the command that displays the attributes of a file.
An automounter is any program or software facility which automatically mounts filesystems in response to access operations by user programs. An automounter system utility, when notified of file and directory access attempts under selectively monitored subdirectory trees, dynamically and transparently makes local or remote devices accessible.
sysstat
is a collection of performance monitoring tools for Linux. It is available on Unix and Unix-like operating systems.
sag - system activity graph [...] DESCRIPTION sag graphically displays the system activity data stored in a binary data file by a previous sar(1) run.