The manual page and help for the rngtest Linux command. The rngtest command verifies data randomness using FIPS 140-2 tests. To run the command on Debian and Ubuntu systems, the rng-tools package must be installed.

The manual page and help for the sar Linux command. Using the sar command, the performance of the various Linux subsystems (CPU, memory, I/O) can be monitored in real time. To use the sar command on Debian and Ubuntu systems, the sysstat package must be installed.

The manual page and help for the mpstat Linux command. The mpstat command outputs statistical information about processors. The command can be used on Debian/Ubuntu systems by installing the sysstat package.

The manual page and help for the realpath Linux command. The realpath command lists the absolute access to the specified file or directory.

The manual page and help for the vnstat Linux command. vnStat is a command-line network traffic monitoring tool. It keeps a log of the hourly, daily and monthly network traffic of the selected interface(s). Data traffic is not measured by capturing packets, but rather they are read from the proc(5) or sys file system, depending on availability, so vnStat can be used on most systems without root privileges.
The program consists of two parts. The vnstat command provides an interface for querying traffic data stored in network device-specific databases, while the vnstatd daemon is responsible for collecting and storing the data. Although the daemon process runs as a continuous service, it idles most of the time between data updates.

The manual page and help for the pwdx Linux command. The pwdx command lists the current working directory of the specified process.

The manual page and help for the watch Linux command.

Manual page and help for the cups-calibrate Linux command. The cups-calibrate program allows you to calibrate the color output of your printers using the Gutenprint CUPS driver. Please note that this program only works with Gutenprint's CUPS driver.

The manual page and help for the iptables-legacy / ip6tables-legacy Linux command. xtables-legacy is the original version of iptables that uses the old getsockopt/setsockopt based kernel interface. This kernel interface has some limitations, so iptables can also be used with the newer nf_tables-based API.

The manual page and help for the nc.openbsd Linux command. The nc (or netcat) utility can be used for almost anything, including things related to TCP, UDP, or UNIX-domain sockets. It can open TCP connections, send UDP packets, listen on any TCP and UDP ports, perform port scanning, and manage both IPv4 and IPv6 networks. Unlike telnet, nc scripts nicely and sends error messages correctly to stderr instead of stdout like telnet does.