• how to capture errors to a file?

    Re: Boot up errors

    How do i create/find the file showing the many boot-up and shutdown errors i get so that i and others may read them? As it is they flash by so that i only catch bits and pieces with no way of sharing with others. Thanks.

  • Once the boot finishes, you have access to more powerful tools to diagnose the boot process and the output you saw scrolling on your screen can be ignored entirely. It was always a simplistic output anyways, and it won’t help troubleshooting anything that these tools can’t.

    That output becomes of use only during failed boot attempts, during which you end up without access to a command prompt. Otherwise, you can ignore it completely and use one of the following more informative reporting tools:

    1. journalctl

    On a systemd enabled OS such as Antergos, this is the primary choice. So, after boot and to get a clearer and more informative picture of the whole boot process along with any errors and warmings, just use the following command:

    $ journalctl -b

    If you read the man page, you’ll learn about the useful -p flag that filters the output to only print messages of a certain level or lower. Your readers will thank you if you do the following instead of the above:

    $ journalctl -b -p4

    This will print only warning messages and below (errors, critical, etc), leaving off any informative messages that usually just add noise to the report and need to be sieved through by your readers, many who will lack the patience.

    2. dmesg

    An alternative to the above command (or if your system is not using systemd) is the good old dmesg command. This is potentially less informative than journalctl above, but not if you have filtered it as I advised you to. So they are essentially equivalent.

    $ dmesg

    Again, If you look in its man page or type invoke dmesg --help you’ll learn about the always useful -l flag, which filters dmesg potentially long output to print only certain message levels. And the -r flag which prints the message level. So, likewise many of us will thank you if you do the following instead of the above:

    $ dmesg -rl warn,err,crit

    Or at the very least:

    $ dmesg -r

    Trivia: The dmesg command is basically the same as journalctl with the -k flag added to it.

    3. Final note:

    Very important! Do not paste only the printed contents of the command. Always show also the command you used to get that output.

  • @Krugar said in how to capture errors to a file?:

    dmesg -rl warn,err,crit

    i will add this to the wiki, as it is missing there… thanks mastermind!

  • This can serve at a general level on system errors:

    journalctl -p 3 -xb


  • journalctl -b -p4 > ~/journal.log create a log file ( journal.log ) under your users home

  • I didn’t think to refer the wiki. And I also completely forgot about know @lots-0-logs pinned post. I need to get more familiar with the current wiki contents. I could have just linked there instead of writing a large reply.

  • Take a look to the wiki! in the first view it a bit hard to get into the format structure , but you will get use to it fast, lso possible to use the formatation-tags by hand, without this “choose and click”…

capture3 Posts 8Views 927
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