How to view syslog in ubuntu?

Question

Follow up from this question, LogBack Syslog not working java

I use command below to view syslog in ubuntu 16.04 but get below result. Is it the correct way to view?

user@xxx:~$ tail -f /var/log/syslog Jun  6 23:08:50 xxx systemd[1]:
Starting Hostname Service... Jun  6 23:08:50 xxx dbus[889]: [system]
Successfully activated service 'org.freedesktop.hostname1' Jun  6
23:08:50 xxx systemd[1]: Started Hostname Service. Jun  6 23:09:41 xxx
gnome-session[2645]: (nautilus:2860): Gtk-WARNING **: Attempting to
read the recently used resources file at
'/home/xxx/.local/share/recently-used.xbel', but the parser failed:
Failed to open file '/home/xxx/.local/share/recently-used.xbel':
Permission denied. Jun  6 23:09:41 xxx org.gtk.vfs.Daemon[2508]:
(gvfsd-recent:15282): Gtk-WARNING **: Attempting to read the recently
used resources file at '/home/xxx/.local/share/recently-used.xbel',
but the parser failed: Failed to open file
'/home/xxx/.local/share/recently-used.xbel': Permission denied. Jun  6
23:09:41 xxx gnome-session[2645]: (zeitgeist-datahub:3069):
Gtk-WARNING **: Attempting to read the recently used resources file at
'/home/xxx/.local/share/recently-used.xbel', but the parser failed:
Failed to open file '/home/seng/.local/share/recently-used.xbel':
Permission denied. Jun  6 23:09:49 xxx gnome-session[2645]:
(nautilus:2860): Gtk-WARNING **: Attempting to read the recently used
resources file at '/home/xxx/.local/share/recently-used.xbel', but the
parser failed: Failed to open file
'/home/xxx/.local/share/recently-used.xbel': Permission denied. Jun  6
23:09:49 xxx org.gtk.vfs.Daemon[2508]: (gvfsd-recent:15282):
Gtk-WARNING **: Attempting to read the recently used resources file at
'/home/xxx/.local/share/recently-used.xbel', but the parser failed:
Failed to open file '/home/xxx/.local/share/recently-used.xbel':
Permission denied. Jun  6 23:09:49 xxx gnome-session[2645]:
(zeitgeist-datahub:3069): Gtk-WARNING **: Attempting to read the
recently used resources file at
'/home/seng/.local/share/recently-used.xbel', but the parser failed:
Failed to open file '/home/xxx/.local/share/recently-used.xbel':
Permission denied. Jun  6 23:17:01 xxx CRON[18877]: (root) CMD (   cd
/ && run-parts --report /etc/cron.hourly)

Try cat /var/log/syslog (small part of the output)

Jun  6 23:37:26 xxx whoopsie[1040]: [23:37:26] online
Jun  6 23:37:26 xxx avahi-daemon[1023]: Registering new address record for 2001:e68:4424:afab:c31f:c843:2351:c58 on wlp6s0.*.
Jun  6 23:37:28 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 4340ms.
Jun  6 23:37:32 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 9080ms.
Jun  6 23:37:41 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 17540ms.
Jun  6 23:37:59 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 34190ms.
Jun  6 23:38:09 xxx NetworkManager[1013]: <warn>  [1496763489.9447] dhcp6 (wlp6s0): request timed out
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9448] dhcp6 (wlp6s0): state changed unknown -> timeout
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9456] dhcp6 (wlp6s0): canceled DHCP transaction, DHCP client pid 19397
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9456] dhcp6 (wlp6s0): state changed timeout -> done
user@xxx:/$ 

Try cat /var/log/syslog | tail -f

user@xxx:/$ cat /var/log/syslog | tail -f
Jun  6 23:37:26 xxx whoopsie[1040]: [23:37:26] online
Jun  6 23:37:26 xxx avahi-daemon[1023]: Registering new address record for 2001:e68:4424:afab:c31f:c843:2351:c58 on wlp6s0.*.
Jun  6 23:37:28 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 4340ms.
Jun  6 23:37:32 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 9080ms.
Jun  6 23:37:41 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 17540ms.
Jun  6 23:37:59 xxx dhclient[19397]: XMT: Solicit on wlp6s0, interval 34190ms.
Jun  6 23:38:09 xxx NetworkManager[1013]: <warn>  [1496763489.9447] dhcp6 (wlp6s0): request timed out
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9448] dhcp6 (wlp6s0): state changed unknown -> timeout
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9456] dhcp6 (wlp6s0): canceled DHCP transaction, DHCP client pid 19397
Jun  6 23:38:09 xxx NetworkManager[1013]: <info>  [1496763489.9456] dhcp6 (wlp6s0): state changed timeout -> done
user@xxx:/$ 

Ballocks

If you try tail /var/log/syslog > /tmp/log and then use gedit to read /tmp/log, have you got same problem ? – Durrett

Why is this tagged "java"? – Caras

@Caras I want to read from java. I have linked my previous question to here. – Ballocks

@Ballocks we shouldn't need to refer to another question to work out what your question is here. – Caras

@romariccrailox I tried that. user@xxx:~$ cd / – Ballocks

user@xxx:/$ tail /var/log/syslog > /tmp/log – Ballocks

Then become user@xxx:/$ again. nothing prompt out. – Ballocks

@Caras Just want to make my post clearer sir. – Ballocks

cat output looks correct, right? How about cat /var/log/syslog | tail -f – Caras

@Caras is same.. – Ballocks

The cat and cat | tail outputs both look correct. What do you think is wrong with it? – Caras

@Caras The output of syslog looked correct (Y) but no idea why the message send from JAVA not receiving in the syslog. Would it because I wrote the wrong logback.xml ? (In my previous question) – Ballocks

@Ballocks well, that's not what you asked. You've given an example syslog that looks fine apart from screwed up newlines. Several people have spent time trying to diagnose your screwed up newlines. – Caras

@Caras I will mark this post as solved. Would you mind to have a look on my previous question ? Thanks. – Ballocks

@Caras Not sure is it because of the syslogHost and facility. – Ballocks

Replying to an older posts, but wanted to mention that there's no need to cat | tail, you can just do tail -f /var/log/syslog to follow the end of the syslog. – Shuffle

journalctl -f 0000000 – Acetous

Answer 1

Looks like you are trying to read syslog from Java, not from an interactive terminal. The text looks like a correct output, but with smashed formatting.

tail -f is good for interactive terminals.

Try cat /var/log/syslog, or just open /var/log/syslog as a file (if your process has enough permissions).

Dorser

are you trying to read file manually from the console, or to read it programmatically from Java? In a first case, use cat /var/log/syslog – Dorser

then just open file from Java like that mkyong.com/java/how-to-read-file-in-java-fileinputstream (make sure to replace file path with /var/log/syslog) – Dorser

There's nothing about Java in your question. If you're using ProcessBuilder or similar to execute tail, then add your code to the question. – Caras

@Caras I follow this tutorial, but no idea how to read that message that was sent from Java in syslog ! – Ballocks

@Ballocks unless you want to read the message using Java, the source of the messages is irrelevant to the question you've asked. – Caras

@Caras ok, forget about that, but what is the way to view syslog ? – Ballocks

did you try cat /var/log/syslog or less /var/log/syslog ? – Dorser

Appreciate your help :) – Ballocks

Answer 2

In a normal terminal window (in Ubuntu, normally Gnome Terminal), what you've done - sudo tail /var/log/syslog should display with newlines such that date/time stamps line up on the left.

Either you're not using a normal terminal window, or some control characters have knocked your terminal into a state where newlines don't display properly.

If you're using something other than a terminal window (perhaps something in your IDE?), then use a normal one instead.

tail -f /var/log/syslog is for following along as the file grows.

You can dump the whole of the file into the terminal with cat /var/log/syslog.

You can interactively scroll through the file with less /var/log/syslog.

If you prefer to use a GUI editor, you can open /var/log/syslog in a text editor like gEdit or Atom, although you would have to run those editors as root -- the responsible thing to do would be to copy the file, make it readable by your user, and open that.

Caras

journalctl -f ??????????? – Acetous