Ubuntu – Less output does not show output in terminal after quitting it

bashlesszsh

Previously, if I ran something | less, and then press q, it used to return me to the prompt with the output of less still visible.

$ seq 1 100 | less
1
2
3
4
:q
$ <prompt here. I can still see the output of less>

But now, after I installed Zsh (with oh-my-zsh. It doesn't work in bash too), the terminal looks like this:

$ seq 1 100 | less
<less shows up, I press :q and it is cleared>
$ <prompt here. Output of less disappears.>

I searched for a less config file and found none. Is there any way I can get less to behave the previous way? Having the output visible is very handy.

Best Answer

seq 1 100 | less -X

see: man less

-X or --no-init
Disables  sending  the  termcap  initialization and deinitialization strings to the terminal. 
This is sometimes desirable if the deinitialization string does something  unnecessary, like clearing the screen.

Related Solutions

Ubuntu – How to make `less` output colors

There are two problems here:

Commands like ls —which auto-detect the colour support— don't find support from pipes
less is set to just display colour codes by default.

Both can be overcome but it's a bit clunky:

ls --color=always | less -R

This isn't ls specific. Many commands that support colour also have an override argument.

A slightly more in-depth answer is that ls is checking whether or not its STDOUT belongs to a real terminal or not. When you pipe things around, the STDOUT is set to the STDIN of the next command.

You can see this at work in the ls source code. It's using the isatty command (a core POSIX interface) to work out what the situation is:

Are colours on by default:

    print_with_color = (i == color_always
                        || (i == color_if_tty
                            && isatty (STDOUT_FILENO)));

Do we try to output in multiple columns:

if (format == long_format)
  format = (isatty (STDOUT_FILENO) ? many_per_line : one_per_line);

//...

if (isatty (STDOUT_FILENO))
  {
    format = many_per_line;
    set_quoting_style (NULL, shell_escape_quoting_style);
    qmark_funny_chars = true;
  }
else
  {
    format = one_per_line;
    qmark_funny_chars = false;
  }

grep does a very similar thing, unless explicitly overridden, it'll detect colour support, with isatty:

color_option = isatty (STDOUT_FILENO) && should_colorize ();

Ubuntu – How to keep the screen contents after quitting less or more

You can use the -X switch:

-X or --no-init
          Disables  sending  the  termcap  initialization and deinitialization strings to the terminal.
          This is sometimes desirable if the deinitialization string does something  unnecessary,  like
          clearing the screen.

Or you could do the following:
For example cat myfile to display the entire file or cat myfile | grep searchterm if you want to search for something specific.

You also could use head -n X or tail-n X to display the first/last X lines of a file.

Best Answer

Related Solutions

Ubuntu – How to make `less` output colors

Ubuntu – How to keep the screen contents after quitting less or more

Related Question