How to redirect output of systemd service to a file?

How to redirect output of systemd service to a file?

StandardOutput= Controls where file descriptor 1 (STDOUT) of the executed processes is connected to. Takes one of inherit, null, tty, journal, syslog, kmsg, journal+console, syslog+console, kmsg+console or socket. The systemd.exec (5) man page explains other options related to logging.

How to redirect standardoutput to systemd journal?

And use the default redirection of StandardOutput= to the systemd journal, so you can read the logs with journalctl -u mydaemon.service. Systemd nicely controls the file growth and file rotation of the log for you. It is unrelated that your service runs as root.

Where does systemd send its output and error to?

Do not use these. systemd already sends the standard output and error of the service process (es) to its journal, without any such settings in the service unit. You can view it with

How to redirect service logs in systemd V240?

# Works only in systemd v240 and newer! StandardOutput=append:/var/log/flume-ng/log1.log StandardError=append:/var/log/flume-ng/log2.log exec means that shell program will be substituted with my_binary program after setting up redirections without forking.

How to set standardoutput in systemd.exec?

In newer versions of systemd there is a relatively new option ( the github request is from 2016 ish and the enhancement is merged/closed 2017 ish) where you can set the values of StandardOutput or StandardError to file:YOUR_ABSPATH_FILENAME. The file:path option is documented in the most recent systemd.exec man page.

Why do I need systemd to run as root?

Systemd nicely controls the file growth and file rotation of the log for you. It is unrelated that your service runs as root. This is necessary because there’s a known issue when some last lines of logging just before a script exists might not be attributed to the script.

How to redirect stdout to logfile-Unix?

If you want to maintain file log between service restarts and just append new logged lines to it, use instead: exec means that shell program will be substituted with /bin/java program after setting up redirections without forking. So there will be no difference from running /bin/java directly after ExecStart=.

How to maintain log files between service restarts?

Note that this way log files contents will be overwritten each time service restarts. StandardOutput/Error systemd directives do not support appending to files. If you want to maintain file log between service restarts and just append new logged lines to it, use instead:

How to redirect a program to a file?

The dup2 call will close and replace file descriptor 2 (stderr, which is usually used by FILE * stderr but not necessarily if you call freopen (x,y,stderr) since that may make FILE *stderr use a different file descriptor). This is how shell programs redirect input and output of programs.

When to redirect the output of a program?

Sometimes, you want to redirect the output of your program to a file–maybe to record it for another program, or because you want to search through it with grep. If you have to do this at the C level, there are a few ways you can accomplish this.

How does dup2 redirect output to a file?

Notice that this code essentially does the same thing as previously: it redirects output to a file. However, there’s a very important difference here. If the process forks-and-execs, the child process will still have its output redirected to file, even after the exec!.

How to get all outputs of systemd managed Python2 script into Journal?

How would I get all outputs of systemd managed python2 script instantly into journal, just like it appears in terminal Oct 30 14:30:41 controller systemd [1]: Starting Tick… Oct 30 14:30:41 controller systemd [1]: Started Tick.

How to add stdout to systemd service file?

The file:path option is documented in the most recent systemd.exec man page. This new feature is relatively new and so is not available for older distros like centos-7 (or any centos before that). I would suggest adding stdout and stderr file in systemd service file itself.

Why does my service run as root in Python?

It is unrelated that your service runs as root. This is necessary because there’s a known issue when some last lines of logging just before a script exists might not be attributed to the script. This would be especially noticeable for a script that just runs a fraction of a second before exiting.