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When you use the command journalctl -p err -b for example, you get an answer that ends with "END". What command do I use to end this and get the opportunity to enter the next command without having to close the window and open a new one?

erik@server ~ $ journalctl -p err -b
-- Logs begin at sön 2019-09-22 20:17:42 CEST, end at sön 2019-09-22 20:20:01 CE
sep 22 20:17:51 server iscsid[1289]: iSCSI daemon with pid=1290 started!
lines 1-2/2 (END)

terminal screenshot

Eliah Kagan
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Skalman65
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3 Answers3

27

A smooth way to end that command is to hit q (for quit). It looks like it is viewed with the viewer less.

You can quit from this command and several other text mode programs with q. In this case and several other cases you can also quit with the ctrl C interrupt, but it is 'more brutal'.

sudodus
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    It seems like it's actually not using `less` itself but a `less`-related library, cause `pidof less` outputs nothing while it's running, and I tried to disable the paging with `LESS=F journalctl -p err -b` but it didn't work. Compare to `git` where both of those work. – wjandrea Sep 22 '19 at 17:25
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    It's using `less`. With `$SYSTEMD_PAGER` and `$PAGER` unset, `journalctl` tries some commands, including (as journalctl(1) says) `less`. But it tries `pager` first. In Debian and Ubuntu, `/usr/bin/pager` is a symlink to `/etc/alternatives/pager`, which is a symlink to `/bin/less` (which users rarely change). So `pidof less` doesn't work but `pidof pager` does. `journalctl` resets `$LESS`, by default to `FRSXMK`, but you can set `$SYSTEMD_LESS`. `FRSXMK` contains `F` but the `F` option only disables paging when neither vertical *nor horizontal* scrolling is needed; see the `S` option. @wjandrea – Eliah Kagan Sep 23 '19 at 10:38
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Read man journalctl. In the Description section, it says:

The output is paged through less by default, and long lines are "truncated" to screen width. The hidden part can be viewed by using the left-arrow and right-arrow keys. Paging can be disabled; see the --no-pager option and the "Environment" section below.

So, you should read man less to learn about this useful tool.

One of the things you can learn from man less is: 

   q or Q or :q or :Q or ZZ
          Exits less.
Lightness Races in Orbit
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waltinator
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    Worth noting that `man` also runs `less` usually, so you’ll need `q` to exit it, too! – Melebius Sep 23 '19 at 12:35
  • Do they document why they page 2 lines of output? Git for example is clever enough to tell when it is only going to show you less than a screen of text and not invoke a superfluous pager. – interfect Sep 24 '19 at 04:02
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    @interfect Per Eliah Kagan's earlier comment on another answer, it would indeed just show the output without paging if it would fit without scrolling, but line wrapping is turned off as well (to avoid ambiguity I guess), and although the example output is not taller than the output terminal, it is wider. – pt314 Sep 24 '19 at 08:08
2

As mentioned in the other answers you can hit q to exit the less pager.

Assuming that the output is short, another option is to directly require the command not to use the pager. In the case of journalctl this is done with the option --no-pager:

journalctl -p err -b --no-pager
Erwan
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