systemd: how to redirect stdout to logfile

Question

I have a systemd service:

[Unit]
Description=My application

[Service]
ExecStart=/bin/java myapp.jar
Type=simple
User=photo

There is an option: StandardOutput= but I don't understand how to use it to write to a file. https://www.freedesktop.org/software/systemd/man/systemd.exec.html

I was expecting to put a filepath somehere but the documentation talks about sockets and file descriptors. seems it needs more configuration than just that keyword.

Where to put the filepath ? I can't find any examples of that use

Thanks

This is a duplicate of Redirect systemd service logs to file... However, the answer there does not answer your question (it doesn't answer the duplicate question either). You might find this answer useful... — don_crissti, Dec 05 '17 at 13:16
my workaround: create a shell launcher that redirect stdout to file and launch that script through systemd. — exeral, Dec 13 '17 at 13:23
@exeral There is also a StandardOutput=file:/path/to/here.log option. — peterh, Feb 06 '19 at 10:27
yea, seems it would do the job now. this feature was added in v236, few days later..! — exeral, Feb 06 '19 at 13:50
Does this answer your question? redirect systemd service logs to file — Cirelli94, May 28 '21 at 10:14

score 21 · Accepted Answer · edited Dec 07 '18 at 17:31

21

Use:

[Unit]
Description=My application

[Service]
ExecStart=/usr/bin/java -jar myapp.jar
Type=simple
User=photo
StandardOutput=file:/var/log/logfile

as documented here: https://www.freedesktop.org/software/systemd/man/systemd.exec.html#StandardOutput=

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:

[Unit]
Description=My application

[Service]
ExecStart=/usr/bin/sh -c 'exec /usr/bin/java -jar myapp.jar'
Type=simple
User=photo

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=.

edited Dec 07 '18 at 17:31

Eugene Lebedev

157

answered Nov 04 '18 at 00:42

Piotr Jurkiewicz

1,960

5

what about append: instead of file:? – Ryan Burnette Jan 29 '19 at 16:55
11

It is worth mentioning append: is available only in systemd 240+. – Hindol Nov 27 '19 at 13:12
3

Also file: is only available in 236+. You can find the version with systemctl --version. At time of writing Amazon Linux 2 ships with 219... – a-h Feb 25 '21 at 13:57

score 10 · Answer 2 · answered Sep 09 '20 at 20:09

10

If your app is a Python script you also need to set

Environment=PYTHONUNBUFFERED=1

Otherwise you will not see any log messages until the buffer is flushed.

answered Sep 09 '20 at 20:09

laktak

5,946

2

I realize this doesn't answer the original question, but as somebody searching for why my (python-based) service isn't logging stdout, this solves my problem. – Brad Grissom May 18 '21 at 16:23

systemd: how to redirect stdout to logfile

2 Answers2