procdata

Lua access to system information provided by the Linux /proc pseudo-file system.

Dependencies

• luaposix
• luafilesystem

API

Notes:

• When a function returns a table, the table keys are boldfaced.
• All functions return nil and an error message in case of error.

procdata.get_platform()

Obtains platform information from /proc/version. Returns a table containing the os type and release, and the gcc version.

procdata.get_total_memory()

Obtains the total amount of memory, from /proc/meminfo. Returns a table containing the total amount of ram and swap memory in bytes.

procdata.get_free_memory()

Obtains the amount of free memory, from /proc/meminfo. Returns a table containing the amount of free ram and swap memory in bytes.

procdata.get_used_memory()

Obtains the amount of used memory, from /proc/meminfo. Returns a table containing the amount of used ram and swap memory in bytes.

procdata.get_num_cpus()

Obtains the number of cpus, from /proc/stat.

procdata.get_clock_speed()

Obtains the maximum frequency available for the system's processors (in MHz).

In order to get a more accurate value, it may use cpuinfo_max_freq, which resides in the cpufreq directory in the /sys/devices hierarchy. If this resource is not availavble, /proc/avcpuinfo is used.

procdata.get_cpu_load()

Obtains current load average numbers, from /proc/loadavg. Returns a table containing the number of queued runnable jobs, averaged over 1 (l1), 5 (l5) and 15 (l15) minutes. When available, returns also the total number of scheduling entities (processes, threads) and the number of currently executing entities.

procdata.get_cpu_times()

Obtains the amount of time (in seconds) that the system spent in different modes, from /proc/stat. Returns a table containg the time spent in user mode, user mode with low priority (nice), system mode and the idle task.

procdata.get_uptime()

Obtains the uptime of the system (in seconds) from /proc/uptime.

procdata.get_process_info(pid)

Obtains information for a running process, given its process ID (pid). This information is gathered from /proc/[pid]/stat and /proc/[pid]/statm. Returns a table containing:

• the process's pid
• its parent's processid (ppid)
• the filename of its executable (comm)
• the process's current state, specified by one character from "RSDZTW", for running (R), sleeping but interruptible (S), waiting for disk and uninterruptible (D), zombie (Z), traced or stopped on a signal (T) and paging (W).
• the amount of time (in seconds) the process has been scheduled in user (utime) and system (stime) mode
• the process's starttime, given in seconds since standard epoch
• memory used by the process (in bytes): total (vmsize), resident (rss) and shared

Note: Because the process's startime provided by /proc/[pid]/stat cannot always be trusted, this function uses the pseudo-directory /proc/[pid]/ creation time, obtained with LuaFileSystem.

procdata.get_processes()

Returns a table (an array) containing the process IDs for all running processes in the system.

This function uses LuaFileSystem to obtain all numerical subdirectories under /proc/.

procdata.get_children(pid)

Returns a table (an array) containing the process IDs for all the immediate children of a process, given its process ID (pid).