apm_available

As apm_available is not a standard Linux command, a formal synopsis does not exist. However, if it were implemented as a simple check, its usage would most likely have been:

apm_available

It is unlikely to have supported significant command-line options or arguments, as its purpose was typically a boolean check for APM presence.

N/A
    No standard parameters exist for this non-standard, legacy command.

apm_available is not a standard, widely distributed Linux command found on modern systems. It likely refers to a utility or script, historically used to determine if Advanced Power Management (APM) features were available or active on a Linux system. APM was an earlier power management specification for laptops and desktop computers, prevalent before the widespread adoption of ACPI (Advanced Configuration and Power Interface).

This command would typically have been part of an older apm utilities package or a simple shell script wrapper that checked the kernel's APM support (often via /proc/apm) or the status of the apmd daemon. Its primary function was to provide a quick programmatic check for power management capabilities, which could then be used by other scripts or applications.

On contemporary Linux distributions, APM has been entirely superseded by ACPI. Therefore, apm_available is obsolete and will not be found as a native command. Modern systems rely on ACPI interfaces and tools like acpi, upower, or systemd-logind for power management status and control.

This command is considered obsolete and is generally not present on modern Linux distributions. Its functionality has been replaced by ACPI and related tools. Attempting to run it on a contemporary system will typically result in a "command not found" error.

If encountered in old documentation or scripts, it signifies reliance on legacy power management infrastructure that is no longer maintained or supported by current kernels and hardware.

While not a standard binary, apm_available would typically have been a shell script that checked for the existence of /proc/apm (a kernel interface for APM information) or the running status of the apmd daemon. Its exit status (e.g., 0 for available, non-zero for not available) would have indicated APM presence.

For checking power management capabilities on modern Linux systems, one would typically use commands like acpi (to query battery status, AC adapter status, thermal information), or interact with upower (via upower -d) or systemd-logind (via loginctl show-session or show-user for idle inhibitors and power management settings). These tools provide more comprehensive information and control over ACPI-based power management.

The Advanced Power Management (APM) specification was developed by Intel and Microsoft in the early 1990s as a BIOS-level interface for operating systems to manage power. Linux kernels began supporting APM early on to enable power-saving features on laptops. The apm_available utility, or similar checks, emerged as part of this ecosystem.

However, APM had limitations, including its BIOS-centric nature and lack of extensibility. In the late 1990s, ACPI (Advanced Configuration and Power Interface) was introduced as a more robust and flexible standard for power management, configuration, and Plug and Play. ACPI delegates more control to the operating system and supports a wider range of power states and features.

Around the early 2000s, Linux kernels and hardware gradually transitioned from APM to ACPI. By the mid-2000s, APM support became a legacy option, and eventually, it was largely removed from modern kernels and distributions. Consequently, tools like apm_available became deprecated and then obsolete.

apm(8), apmd(8), acpi(1), upower(7), systemd-logind(8)