[英]Python script runs flawless when executed in shell, but throws unicode errors when executed as systemd service
[英]Systemd service does not write python script to file, python script runs nominally when executed from cli
使用覆盆子pi零w,设置一个脚本,用于监视bme280传感器,并将值写入文件。 当从命令行启动脚本时,这非常有效,当通过systemd启动脚本时,不会写入文件。 请在下面找到脚本和systemd服务。
已将标准输出设置为绝对路径而没有运气,python脚本写入指令也设置为绝对路径。
系统服务:
[Unit]
Description=bme280 sensor log startup
After=network.target
[Service]
ExecStart=/usr/bin/python3 -u /home/pi/bme.py
WorkingDirectory=/home/pi
StandardOutput=file:/home/pi/senselog.csv
StandardError=inherit
Restart=always
User=pi
[Install]
WantedBy=multi-user.target
python脚本:
import time
from time import strftime
import board
import busio
import adafruit_bme280
# Create library object using our Bus I2C port
i2c = busio.I2C(board.SCL, board.SDA)
bme280 = adafruit_bme280.Adafruit_BME280_I2C(i2c,address=0x76)
# OR create library object using our Bus SPI port
#spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
#bme_cs = digitalio.DigitalInOut(board.D10)
#bme280 = adafruit_bme280.Adafruit_BME280_SPI(spi, bme_cs)
# change this to match the location's pressure (hPa) at sea level
bme280.sea_level_pressure = 1013.25
with open("/home/pi/senselog.csv", "a") as log:
while True:
temp_h = bme280.temperature
humidity = bme280.humidity
pressure = bme280.pressure
log.write("{0},{1}\n".format(strftime("%Y-%m-%d %H:%M:%S"),str([temp_h,humidity,pressure])))
time.sleep(60)
如果我删除了senselog.csv文件,那么在启动时,systemd服务会创建文件,但没有数据,任何帮助都表示赞赏。
只有systemd
版本236才能使用StandardOutput
的file
属性。您有什么版本?
pi@wifi-relay:~ $ systemd --version
systemd 232
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN
如果它低于版本236并且您不能/不想升级,您只需将ExecStart
行更新为:
/usr/bin/python3 -u /home/pi/bme.py >1 /home/pi/senselog.csv
...然后将StandardOutput
线恢复为默认值。
因此,解决方案是在python脚本中实际调用我们正在写入的文件上的.close(),然后systemd服务按预期工作。 大声呼吁这个帖子: https ://askubuntu.com/questions/83549/python-script-wont-write-data-when-ran-from-cron最后一个答案= f.close()
和工作脚本文件:
from time import strftime
import board
import busio
import adafruit_bme280
# Create library object using our Bus I2C port
i2c = busio.I2C(board.SCL, board.SDA)
bme280 = adafruit_bme280.Adafruit_BME280_I2C(i2c,address=0x76)
# OR create library object using our Bus SPI port
#spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
#bme_cs = digitalio.DigitalInOut(board.D10)
#bme280 = adafruit_bme280.Adafruit_BME280_SPI(spi, bme_cs)
# change this to match the location's pressure (hPa) at sea level
bme280.sea_level_pressure = 1013.25
with open("/home/pi/senselog.csv", "w") as log:
while True:
temp_h = bme280.temperature
humidity = bme280.humidity
pressure = bme280.pressure
log.write("{0},{1}\n".format(strftime("%Y-%m-%d %H:%M:%S"),str([temp_h,humidity,pressure])))
log.close()
time.sleep(60) ```
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