hcitool lescan scripting question...
Hello,
now this may seem like a silly question, but I have been trying to do some simple shell scripting with hcitool's LE scan and redirected its out and err streams. The result is not quite what I am expecting:
hcitool lescan --duplicates > /tmp/lescan.out
This will create the output file immediately, but it remains empty until the hcitool process terminates. Only then does the entire output get flushed. Any idea why the output does not get written immediately? Ie. why I can't "tail -f /tmp/lescan.out"?
My intention was to pipe the output through a shell script to add a timestamp to each line, so I get a simple log during testing. I did not want to modify hcitool/write my own C program just for this purpose.
Kind regards,
Edmund
Hi Edmund,
Quoted 9 lines · Edmund
Hello,
now this may seem like a silly question, but I have been trying to do some simple shell scripting with hcitool's LE scan and redirected its out and err streams. The result is not quite what I am expecting:
hcitool lescan --duplicates >
/tmp/lescan.out
Quoted 8 lines
This will create the output file immediately, but it remains empty until the hcitool process terminates. Only then does the entire output get flushed. Any idea why the output does not get written immediately? Ie. why I can't "tail -f
/tmp/lescan.out"?My intention was to pipe the output through a shell script to add a timestamp to each line, so I get a simple log during testing. I did not want to modify hcitool/write my own C program just for this purpose.
This is due to stdout buffering. Try with stdbuf:
stdbuf -oL hcitool lescan --duplicates > /tmp/lescan.out
Signature · 2 lines
Best regards, Szymon Janc