ledcontrol.conf - configuration file for ledd's default startup script

The file ledcontrol.conf is the configuration file for startup.sh(8), the default startup script for ledd(8), part of the ledcontrol package. ledcontrol.conf configures under what circumstances what LEDs are lighted. It is parsed by startup.sh as a shell script, so blank lines and lines with a number sign (``#'') are ignored. It can therefore also include normal shell commands for more complex actions. Everything written to standard output is parsed by ledd as commands and everything written to standard error is logged via the chosen logging mechanism on a warning level.

The default file is pretty well commented, so you should be able to configure it just by looking at it.

The configuration itself is done by setting environment variables. The format is ``VARIABLE="option"''. All options should be set.

STARTUP_ANIM=[YES|NO]

If set to YES, a short animation (about 1 second) is flashed when starting ledd. It is ignored if started in X, as this might leave the LEDs in an incorrect state. It is done in the background, so it doesn't slow the booting.

USE_BACKGROUNDING=[YES|NO]

If set to YES, then some slow tests (eg. pinging a remote host that isn't responding) are done in the background so as not to delay other checks. This is automatically disabled if using bash 2.x.x as it has a bug that makes it freeze. It is safe to leave this on.

MINIMUM_DELAY=VALUE

Sleep VALUE seconds at minimum between the checks. This gives the resolution of the check timings (a scheduled check can be delayed at most VALUE seconds). 5 is a reasonable value.

Note that you will probably get a disk-access every VALUE seconds (see startup.sh(8) section SILENCING for details).

DEFAULT_SETTINGS="command"

These settings are set at the beginning. (See ledd(8) section COMMANDS)

The different tests are defined by four variables per test. Each one is suffixed with an underscore and a number. The numbers have to rise from 1 up (you're not allowed to skip numbers). The variables are as follow:

COMMAND_nn

Command to test the condition. This can be any command available on the system or a build-it check (see BUILT-IN CHECKS below). It should not print anything to stdout (except in special conditions, see WRITING SCRIPTS below). Errors may be printed to stderr.

SUCCESS_nn

Command to give ledd if COMMAND_nn returns successfully (exit code 0). If an arbitrary number is to be indicated (using commands "frequency" or "dutycycle", see ledd(8)), the last argument (the value) should be omitted.

FAILURE_nn

Command to give ledd if COMMAND_nn returns unsuccessfully (exit code non-zero). If an arbitrary value is to be indicated this variable may be ignored, but must be present (eg. "nop").

DELAY_nn

Minimum time between tests. The resolution of this is determined by MINIMUM_DELAY.

Ledcontrol offers certain common checks built-in. The command names are prefixed with led_. They can be used in the checks as any other commands. The following checks are boolean checks.

led_ppp

Check for a PPP-link. Returns true if a network interface with the name ppp0 to ppp9 is found.

led_ping host

Returns true if host replies to a ping packet. ping(8) must be available on the machine. This function uses backgrounding, if available.

led_file file(s) ...

Returns true if every one of file(s) exist. file(s) may contain wildcards (in that case at least one file has to match each pattern).

led_size file min [max]

Returns true if file exists and its size is greater or equal to min and (optionally) less than max. This can be used to detect mail in someone's mailbox.

The following checks set the LED to indicate a number. The SUCCESS_nn command should be either type "set xxx frequency" or "set xxx dutycycle", where the last argument (the value) is omitted.

led_load

Indicate the current system load (1 minute average). FAILURE_nn is ignored, but must be present.

led_netload iface type

Indicate current network load on interface iface. type may be "IN", "OUT", or "BOTH" for inbound traffic, outbound traffic or both together. The value is given as kB/s (kilobytes per second). The longer DELAY_nn is, the more accurate the value. Returns false if no such interface exists.

If you want to use the scriptability to the full extent, I suggest you write custom "built-in" functions. This can be done either by adding it to /usr/share/ledcontrol in a file ending in .sh (it doesn't have to be executable) or by writing it in ledcontrol.conf. In both cases it is sourced by startup.sh at startup. Read the existing scripts for examples.

The following environment variables are available to the function:

LEDDSCRIPTS

Directory in which all the scripts should be located, including startup.sh.

SUCCESS

The command to be given on successful exit value. The function may change this to give another command (it is restored between calls).

FAILURE

The command to be given on unsuccessful exit values. The function may change this to give another command.

COMMAND

The whole command that was executed to start the function. Note that command line arguments are also available in $1, $2, etc.

COUNT

Number part of COMMAND_nn. Can be used to store variables between calls (see Storing variables between calls below). This must not be changed!

USE_BACKGROUNDING

Set to YES if slow checks should be backgrounded (see Backgrounding below).

If you want to make a script that outputs an arbitrary number, you should append the number to the environment variable SUCCESS and return 0 (for example load.sh, netload.sh).

The function may use almost any variables internally, but must not depend on them staying same between calls, as there might be several tests using the function. Instead you can use variables beginning with the function name and with $COUNT appended to it. This can be done as follows (other means exist in new versions of bash):

# Read previously saved value to $LOCAL eval 'LOCAL=LED_NAME_DESC_'$COUNT

# Store value from $LOCAL for future use eval 'LED_NAME_DESC_'$COUNT'=$LOCAL'

Tests which may take many seconds to complete (eg. ping when remote host is not responding) should check whether the variable USE_BACKGROUNDING is set to "YES" and in that case make the test in a background process. The function itself should set SUCCESS to "nop" and return successfully and the subprocess check the condition and echo $SUCCESS or $FAILURE depending on the result. Note that when making the background process, you should always check whether the old process is still running.

The background process can be made by

# Retrieve old PID if test -z "$PID" -o ! -e "/proc/$PID" ; then ( commands ) & PID=$! fi # Store PID

Look at the existing scripts. For basic boolean checks, see eg. file.sh, size.sh and ppp.sh. For examples of arbitrary number indication, see load.sh, or a more complex example with variable storing in netload.sh. For an example of backgrounding, see ping.sh.

Example configuration file:

# Give startup animation STARTUP_ANIM=YES

# Use backgrounding (automatically disabled if dangerous) USE_BACKGROUNDING=YES

# Minimum delay of 5 seconds is reasonable MINIMUM_DELAY=5

# We use Caps Lock and Scroll Lock, so set them off. DEFAULT_SETTINGS="set c1s1 off"

# Two tests: # Scroll Lock indicates the current system load # Caps Lock is lighted when a ppp-link is up and blinks when # "somehost.example" responds. COMMAND_1="led_load" SUCCESS_1="set s5 frequency 0.8 1000 1.9 100" FAILURE_1="nop" # Ignored, but must be present. DELAY_1=10 # Not so critical check.

COMMAND_2="led_ppp" SUCCESS_2="set c4 on" FAILURE_2="set c4c6 normal" # We assume that if this fails, # ping will also fail. DELAY_2=5 # For immediate response

COMMAND_3="led_ping somehost.example" SUCCESS_3="set c6 blink 500" FAILURE_3="set c6 normal" DELAY_3=20 # Not so critical check.

/etc/ledcontrol.conf

default configuration file location

/usr/share/ledcontrol/

location of the default startup script startup.sh and other scripts

startup.sh(8), ledd(8), ledd.conf(5), ledcontrol(1), bash(1), ping(8)

Ledcontrol was written by Sampo Niskanen <sampo.niskanen@iki.fi>. You can get the latest version of ledcontrol from http://www.iki.fi/sampo.niskanen/ledcontrol/

bash version 2.xx.xx has a bug in it that causes startup.sh to lock up if backgrounding is used. From version 0.5.0 up this has been checked by startup.sh and if a bad version of bash is being used the variable USE_BACKGROUNDING is automatically set to "NO".

The default startup script may cause a disk-access every MINIMUN_DELAY seconds. See startup.sh(8) for more info.