Issue
I have a little python tool useable in bash command, on a embedded linux (on a seismic digitizer). In my example, that's the tool which call the sensors (in this case, voltage sensors) then out the results in the terminal. The tool is just 3 lines of script that call a library:
#!/usr/bin/python
import sys
from ccube.apps.ccube_sensors import main
sys.exit(main())
I really don't know what is "ccube.apps.ccube_sensors". Nevermind, I just want the print result in bash to be inject in a txt file, but doing a ">" doesn't work.
Here the use of the tool :
/usr/bin/ccube-sensors voltage -m all > test.log
(-m is or "machine" format out, "all" is all sensors)
in the terminal, it produce :
system=12.60V battery=3.25V
But test.log still empty. Notice : the digitizer run a old 2.7 python and this is a arm proc device with a unknow embedded linux.
Solution
The issue is that your Python abuses the sys.exit() function to print its output. As a result, it prints the string it receives as a parameter on stderr and exits with a non-successful error status. As a result of writing on stderr, rather than stdout, the messages are not redirected by your > test.log at the end of your command.
In order to leave the Python unchanged, you would need to redirect stderr as follows - note the 2 denoting stderr:
/usr/bin/ccube-sensors voltage -m all 2> test.log
But the better solution, IMHO, is to change your Python to stop abusing sys.exit() and use the regular print() function, then your original bash script will work:
#!/usr/bin/python
from ccube.apps.ccube_sensors import main
print main()
I don't know Python 2.7, but I believe that's how print() used to work.
Answered By - Mark Setchell Answer Checked By - Dawn Plyler (WPSolving Volunteer)