is-up

Check the status of the specified website

$ is-up [example.com]

The command is-up is not a standard Linux utility, and therefore does not have a predefined synopsis. Its usage would depend entirely on its custom implementation as a script or alias within a specific environment.

The command is-up is not a standard, universally available Linux command. Its name suggests a utility designed to determine if a specific system component (e.g., a network host, a service, or a network interface) is operational or 'up'.

On Linux, such 'is-up' functionality is typically achieved using a combination of well-established utilities. For checking network host reachability, tools like ping are used. To verify network interface status, ip link show or ifconfig (though deprecated) are common. Service status is managed and queried via systemctl status for systemd-based systems, or service for older init systems. Port listening status can be checked with netstat -tuln or ss -tuln.

Therefore, while 'is-up' itself isn't a native command, the concept it represents is fundamental to system administration, relying on a suite of existing commands.

The most significant caveat is that is-up is not a standard Linux command. If encountered, it likely refers to a custom script, an alias, or a niche utility unique to a specific environment. Its functionality, arguments, and behavior would vary wildly based on its specific implementation, making it non-portable and potentially unpredictable without examining its source code or documentation specific to that environment.

Although is-up is not a standard command, the concept of checking if something is 'up' is fundamental. Here are common scenarios and the standard Linux commands used to achieve them:

Check if a Host is Reachable:
Use ping -c 1 hostname_or_ip. A successful return code (0) indicates reachability.

Check if a Network Interface is Up:
Use ip link show interface_name and look for 'UP' in the output. For example, ip link show eth0.

Check if a Systemd Service is Running:
Use systemctl is-active service_name or systemctl status service_name. The is-active command returns 0 for active, non-zero otherwise.

Check if a Port is Listening:
Use ss -tuln | grep :port_number. If output is returned, the port is listening. For example, ss -tuln | grep :80.

As is-up is not a standard Linux command, it does not have a formal development history or widespread usage evolution like core utilities. Any 'history' would be confined to the specific context where it was created or adopted as a custom tool, perhaps for simplifying common status checks in a particular system setup.

ping(8), ip(8), ss(8), netstat(8), systemctl(1), nc(1)