fancontrol Error message if INTERVAL not an integer, bug if INTERVAL a negative non-integer

[Randy]

Found in fancontrol 1:3.3.4-2ubuntu1 (fancontrol script Version 0.70, also exists in Version 0.71).

If the config file has an INTERVAL that's NOT an integer (found with INTERVAL=0.25) then bash's [ ] test (currently on line 77: if [ "$INTERVAL" -le 0 ] ) will fail (since -le expects integers) and output an error message, but fancontrol continues.

Fancontrol seems to work correctly with a non-integer positive INTERVAL, since "GNU `sleep' accepts arbitrary floating point numbers."

If INTERVAL is a negative non-integer (like -0.5) then the test for negative numbers will fail, fancontrol will NOT exit, but sleep will fail/crash. Fancontrol will still run, but with no sleep, using much more CPU resources/time.

Output of fancontrol with INTERVAL=0.25

    Loading configuration from /etc/fancontrol ...
    /usr/sbin/fancontrol: line 77: [: 0.25: integer expression expected

    Common settings:
      INTERVAL=0.25

    Settings for hwmon2/device/pwm3:
      Depends on hwmon2/device/temp2_input
      Controls hwmon2/device/fan3_input
      MINTEMP=30
      MAXTEMP=45
      MINSTART=150
      MINSTOP=70
      MINPWM=70
      MAXPWM=175

    Settings for hwmon2/device/pwm1:
      Depends on hwmon1/device/temp1_input
      Controls hwmon2/device/fan1_input
      MINTEMP=5
      MAXTEMP=25
      MINSTART=110
      MINSTOP=110
      MINPWM=110
      MAXPWM=255

    Enabling PWM on fans...
    Starting automatic fan control...

Output if INTERVAL=-1.5

    Loading configuration from /etc/fancontrol ...
    /usr/sbin/fancontrol: line 77: [: -1.5: integer expression expected

    Common settings:
      INTERVAL=-1.5

    Settings for hwmon2/device/pwm3:
      Depends on hwmon2/device/temp2_input
      Controls hwmon2/device/fan3_input
      MINTEMP=30
      MAXTEMP=45
      MINSTART=150
      MINSTOP=70
      MINPWM=70
      MAXPWM=175

    Settings for hwmon2/device/pwm1:
      Depends on hwmon1/device/temp1_input
      Controls hwmon2/device/fan1_input
      MINTEMP=5
      MAXTEMP=25
      MINSTART=110
      MINSTOP=110
      MINPWM=110
      MAXPWM=255

    Enabling PWM on fans...
    Starting automatic fan control...
    sleep: invalid option -- '1'
    Try 'sleep --help' for more information.
    sleep: invalid option -- '1'
    Try 'sleep --help' for more information.
    sleep: invalid option -- '1'

[sleep error repeats until fancontrol killed]

Originally found/tested in Linux Mint 17.2, package from the Ubuntu (universe) repository, but it's a bash error so should exist on any system fancontrol runs on.

[Randy (xen2050)]

I think I've got a fix, by changing the test for a negative number to use [[ ]] and a regex to check for only positive numbers (with or without a decimal), and not zero (matching non-zero real numbers in one regex was getting messy). Using this:

if ! [[ "$INTERVAL" != "0" && "$INTERVAL" =~ ^[0-9]+([.][0-9]+)?$ ]]

It will match non-numbers, double-decimals (2.5.3), and any negative signs, and 0. It will also match decimal numbers without a leading zero like .5 , but maybe that's good enough.

It will let fancontrol work with a floating point/decimal INTERVAL without the error message.

I'll attach a patch file for the fancontrol script (not sure if the file names/paths at the top are correct though)

(Another idea was to change the sed call when INTERVAL is assigned, but that wouldn't allow error checking/reporting)

# If earlier patch & my previous 2 comments still appear, please delete them, had errors. Delete this line too :-)