164

I've found one way so far: less +G filename, but it's scroll up only with up key line by line. What's more powerful less usages which provide scrolling by page, pattern search backward and so on?

10 Answers 10

217

I'm sure someone else has a better answer, but

With "less" after you've opened the file:

G goes to the bottom of the file

^b goes up one page

? searches backwards.

As you said, you can open the file with +G and then use ? and ^b to scroll up. There are likely clever awk things you can do to achieve the same thing in a script.

  • 3
    Ctrl-b works, but b (by itself) also does. – Dennis Williamson Jun 16 '10 at 13:31
  • Oops! I'm so conditioned to use vi keys that I just use those in less as well. Yes -- b moves you up a page in less, but only backwards one word at a time in vi. I'm impatient; I want a page at a time, and my walnut sized brain can't remember if I'm in vi or less sometimes... – chris Jun 16 '10 at 14:06
  • 2
    less your file, then type 'h' => you get a nice per-operation manual. Very neat, no need for external guides or the manpage IMO. – Kharski Jan 21 '15 at 14:32
  • 5
    in fact, ? = shift + /, / is to search forwards. – HongboZhu May 23 '16 at 13:11
  • In fact Shift + G goes to the bottom of the file – Alex78191 Jun 6 '18 at 21:57
80

For variety, if you actually want/need to read a file backwards (last line first):

tac filename | less
  • 1
    That's mostly a linux / gnuism... – chris Jun 16 '10 at 13:58
  • 53
    Fun fact: tac is cat backwards – dKen Mar 21 '16 at 15:57
  • 6
    This was my childhood cat's name. I don't think I realized why until now. – vaughan Nov 26 '17 at 12:46
  • Anybody heard of anything like ztac for gzipped files (ie zcat but backwards)? – irbanana Dec 4 '18 at 23:16
  • 1
    @irbanana: One way. But it doesn't save any time on large files because the whole file has to be decompressed. – Dennis Williamson Dec 4 '18 at 23:47
7

w goes up by page. ? does reverse search. h brings up online help.

3

tail -r | less

I don't know why anyone didn't think of this one. Tail grabs the end of a file really easy. Is -r not a common option?

  • Using tail (GNU coreutils) 8.13 on Ubuntu 12.02 here. No such option as -r. – JHH Mar 30 '16 at 6:47
  • I think tail -r is a BSD/macOS thing - those environments don't have tac. – fzzfzzfzz Apr 27 '17 at 15:24
2

While using more for example journalctl -xe using space bar takes you 1 page down. That worked for me. Hope this helps.

2

use:

less +F /path/to/your/file

that's less but starting from the bottom. Use the up arrow key to go backwards line by line or ctl+b to go page by page.

  • 3
    This not only goes to the end of the file, it waits for additional output at the end, like tail -f. If this isn't what you want, you should use +G instead. – Michael Hampton Aug 1 '18 at 18:31
  • you're right @MichaelHampton – Ruben Estrada Aug 1 '18 at 18:49
2

I'm surprised nobody brought this up before, but:

?pattern searches for pattern backwards.

N finds the previous match of the pattern (that is, searching backwards).

For reference, /pattern searches for pattern forward and n finds the next match of the pattern. That's the way the search is commonly used.

1

Another alternative, after you have started less on a file:

alt + "end-key"

With "end-key" I mean the key that is usually located below the "home-key" on a keyboard.

-1

If you're looking for something specific, this might do it:

cat yourfile.txt | grep "something specific" | less

I use it for searching log files. It's still in the 'wrong' order though, but much shorter.

After reading Dennis Williamson's answer, that's my new method =)

  • I don't need cat with grep -- grep $StRING $FILENAME | less – Lee Gee Nov 10 '16 at 8:55
  • Imho, that's an absolutely different question. – Yaroslav Nikitenko Mar 23 '17 at 7:57
-1

Perhaps some people did not understood what dr01 meant. I try to put it in other words.

  • Open the file in less
  • Forward search: Enter the key /
  • Backward search: Enter the key ?
  • For both of the preceding: Enter your search term now
  • Press enter
  • Press n to search for the next finding
  • Press N to search for the previous finding

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