Monit is a utility for managing and monitoring processes, programs, files, directories, and devices on a Unix system. It conducts automatic maintenance and repair and can execute meaningful causal actions in error situations. It can be used to monitor files, directories, and devices for changes, such as timestamps changes, checksum changes, or size changes. It is controlled via an easy to configure control file based on a free-format, token-oriented syntax. It logs to syslog or to its own log file and notifies users about error conditions via customizable alert messages. It can perform various TCP/IP network checks, protocol checks, and can utilize SSL for such checks. It provides an HTTP(S) interface for access.
MultiTail lets you view one or multiple files like the original tail program. The difference is that it creates multiple windows on your console (with ncurses). Merging of 2 or more log files is possible. It can also use colors while displaying the log files (through regular expressions) for faster recognition of what is important. It can also filter lines (again with regular expressions). It has interactive menus for editing given regular expressions and deleting and adding windows. One can also have windows with the output of shell scripts and other software. When viewing the output of external software, MultiTail can mimic the functionality of tools like 'watch'.
Ganglia is a scalable distributed monitoring system for high-performance computing systems such as clusters and grids. It is based on a hierarchical design targeted at federations of clusters. Ganglia is currently in use on over 500 clusters around the world and has scaled to handle clusters with 2000 nodes.
The libstatgrab library provides an easy-to-use interface for accessing system statistics and information. Available statistics include CPU, Load, Memory, Swap, Disk I/O, and Network I/O. It was developed to work on Linux, FreeBSD, and Solaris. The package also includes two tools: saidar provides a curses-based interface for viewing live system statistics, and statgrab is a sysctl-like interface to the statistics.
System Configuration Collector collects and classifies most of your Unix/Linux/BSD configuration data in flat files called snapshots. This allows changes in snapshots of consecutive runs to be detected. These changes are added to a logbook, which is helpful for administrators during troubleshooting and for auditors during audits. Snapshots and logbooks are also available in HTML format. All data can be send to an SCC server, where a Web interface provides access to summaries and supports comparing snapshots of different servers and searching of all data. A WMI-based Windows client is also available.
Munin is a system to gather and graph all sorts of information. You can install a node on the various machines in your network, as well as on a central server. The nodes will know how to extract various kinds of information, such as load average and bandwidth usage, and will wait for the server to request these values. The output is in HTML format. The server can optionally send notifications if any of the values move outside of a specified range (and when they move back into it).