Combining tail && journalctl

Question

I'm tailing logs of my own app and postgres.

tail -f /tmp/myapp.log /var/log/postgresql/postgresql.main.log

I need to include pgpool's logs. It used to be syslog but now it is in journalctl.

Is there a way to tie tail -f && journalctl -f together?

Answer 1

You could use:

journalctl -u service-name -f

-f, --follow

Show only the most recent journal entries, and continuously print new entries as they are appended to the journal.

Here I've added "service-name" to distinguish this answer from others; you substitute the actual service name instead of the text service-name.

Answer 2

You could forward your log entries to journal:

systemd-cat tail -f /tmp/myapp.log /var/log/postgresql.log

and then use journalctl -f... though as Mark mentioned, that will print all journal entries.

---

One way to filter only the messages from those logs and from that particular unit is to use a distinct SYSLOG_IDENTIFIER i.e. edit the unit file and under the [Service] section add e.g.

SyslogIdentifier=my_stuff

restart the unit then run systemd-cat with the same identifier

systemd-cat -t my_stuff tail -f /tmp/myapp.log /var/log/postgresql.log

and finally query the journal only for that particular identifier:

journalctl -f -t my_stuff

Answer 3

If you have bash available, you can use process substitution as one of the tail parameters:

tail -f /tmp/myapp.log /var/log/postgresql/postgresql.main.log <(journalctl -f)

Answer 4

try something like:

tail -f /tmp/myapp.log >> /tmp/tail.log &
journalctl -f >> /tmp/tail.log &
tail -f /tmp/tail.log

Answer 5

Using journaltail:

journaltail --unit pgpool.service /tmp/myapp.log /var/log/postgresql/postgresql.main.log

I just threw the script together an hour ago after looking for a solution at stackoverflow et al.