回复: 回复: Is it possible to send a string to the journal of one specific systemd unit

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python works fine!

Thanks a lot, Mantas.

BR.

发件人: Mantas Mikulėnas <grawity@xxxxxxxxx>
发送时间: 2021年10月23日 6:42
收件人: DHAIY DHAIY <dhaiy@xxxxxxx>
抄送: systemd-devel@xxxxxxxxxxxxxxxxxxxxx <systemd-devel@xxxxxxxxxxxxxxxxxxxxx>
主题: Re: [systemd-devel] 回复: Is it possible to send a string to the journal of one specific systemd unit

This option was added with util-linux v2.25 in 2014. If you're using an older version or the Busybox `logger` instead, well, it won't have that.

The alternative is to write your own C tool that uses libsystemd and calls sd_journal_send() with the correct fields (libsystemd is definitely going to be present), or a Python tool that uses systemd.journal.send(). (Or maybe call libsystemd through python ctypes or whatever other FFI mechanism is available.)

On Fri, Oct 22, 2021 at 4:32 PM DHAIY DHAIY <dhaiy@xxxxxxx> wrote:

Thanks a lot Mantas.

But in my sytem, logger does not have "--journal".

Are you aware of other tools from bash which can be used?

BR

发件人: Mantas Mikulėnas <grawity@xxxxxxxxx>
发送时间: 2021年10月22日 18:45
收件人: DHAIY DHAIY <dhaiy@xxxxxxx>
抄送: systemd-devel@xxxxxxxxxxxxxxxxxxxxx <systemd-devel@xxxxxxxxxxxxxxxxxxxxx>
主题: Re: [systemd-devel] 回复: Is it possible to send a string to the journal of one specific systemd unit

If you have root privileges (i.e. UID 0), then yes, you can send a journal message with the "OBJECT_SYSTEMD_UNIT=myservice.service" field and journalctl will automatically look for that.

In C, specify the field when calling sd_journal_sendv(); in bash you can use `logger --journal`:

(echo "OBJECT_SYSTEMD_UNIT=sshd.service";
echo "MESSAGE=Hello world!") | sudo logger --journal

On Fri, Oct 22, 2021 at 11:43 AM DHAIY DHAIY <dhaiy@xxxxxxx> wrote:

Saying we have a systemd unit named "myservice".

we can use journalctl -u myservice to inspect the logs generated by myservice.

But is there a way to insert one string from command-line into myservice's journal so that it can be seen by journalctl -u myservice later?

发件人: DHAIY DHAIY
发送时间: 2021年10月22日 16:40
收件人: systemd-devel@xxxxxxxxxxxxxxxxxxxxx <systemd-devel@xxxxxxxxxxxxxxxxxxxxx>
主题: Is it possible to send a string to the journal of one specific systemd unit

Saying we have a systemd unit named "myservice".

we can use journalctl -u myservice to inspect the logs generated by myservice.

But is there a way to insert one string from command-line into myservice's journal so that it can be seen by journalctl -u myservice later?

--

Mantas Mikulėnas

Mantas Mikulėnas