pigpio Can't lock /var/run/pigpio.pid

Question

Trying to run the pigpio example program freq_count_1 I get the error Can't lock /var/run/pigpio.pid. The gpiotest program, however, runs as expected. Below you can see what I did. I have a Raspberry Pi 2 running Jessie.

gcc -Wall -pthread -o freq_count_1 freq_count_1.c -lpigpio -lrt`
rm -f /var/run/pigpiod.pid`
./freq_count_1 4 7 -r2 -s2`

Monitoring GPIO pins: 4 and 7
Sample rate 2: micros
refresh rate 2 deciseconds

2015-11-27 13:47:24 initInitialise: Can't lock /var/run/pigpio.pid

I'm getting this problem when killing my program ungracefully. It seems the missing gpioTerminate() call in the end causes a file lock not to get unlocked or so. Don't have a fix yet, do you? — Julian F. Weinert, Mar 23 '16 at 15:46

score 22 · Answer 1 · edited Mar 06 '19 at 07:03

22

You need to stop the pigpio daemon if you run a program directly linked with the pigpio C library.

In effect your program becomes the pigpio daemon and only one may be running at a time.

So

sudo killall pigpiod

Then run your C program.

While your C program is running it acts as the daemon, so you can still run gpiotest and any of the pigs commands, e.g. pigs pigpv (software version), pigs hwver (hardware version), pigs t (current tick).

edited Mar 06 '19 at 07:03

Ghanima

15,855
15
61
119

answered Nov 27 '15 at 13:00

joan

71,024
5
73
106

Many thanks for a rapid and clear answer that did the trick. – user37342 Nov 27 '15 at 13:17

score 3 · Answer 2 · answered Mar 05 '19 at 23:56

3

You need to find out which other process is using it. Then kill that process.

This issue is documented on the FAQ page linked below:

http://abyz.me.uk/rpi/pigpio/faq.html#Cant_initialise_pigpio_library

answered Mar 05 '19 at 23:56

user566245

131
3

The command ps aux | grep pigpiodcan be replaced with pgrep pigpiod – MatsK Mar 06 '19 at 05:01

pigpio Can't lock /var/run/pigpio.pid

2 Answers2