How to make Less indicate location in percentage

I now aim to show the percentage sign also when you run, for example, the command

man emacs

If you run it, you get 'byte 3300' for instance.

Alex's answer suggests me that we need to make a separate shell function by

man "$1"| col -b > /tmp/manual
less /tmp/manual

where $1 refers to the first parameter.

The new problem is at the thread. Thanks to Yuliy for the crux move!

Solution

A less manual version of knitatoms' answer combined with Alex Marteilli's answer works quite well: pass the +Gg option to less via its pager option.

For example, try

man -P 'less -s -M +Gg' man

This can be effected permanently by putting

export MANPAGER='less -s -M +Gg'

in one of your shell configuration files (above syntax is for Bash and ZSH). Now, for example, man man displays the percentage as you wanted!

Warning

You should not put the +Gg in the LESS variable! For example, doing

export LESS='-M +Gg'

will cause problems when reading very large files. For example,

yes | LESS='-M +Gg' less

does not work very well ...

Explanation

As other answers have explained, the problem is that less can't say what percent into the file you are until it knows how long the file is, and it doesn't read to the end of the file by default when reading from a pipe.

From the OPTIONS section of man less:

+      If  a command line option begins with +, the remainder of that
       option is taken to be an initial command to less.   For  exam‐
       ple, +G tells less to start at the end of the file rather than
       the beginning, and +/xyz tells it to start at the first occur‐
       rence of "xyz" in the file.  As a special case, +<number> acts
       like +<number>g; that is, it starts the display at the  speci‐
       fied  line  number (however, see the caveat under the "g" com‐
       mand above).  If the option starts with ++, the  initial  com‐
       mand  applies  to  every file being viewed, not just the first
       one.  The + command described previously may also be  used  to
       set (or change) an initial command for every file.

The g means "return to the beginning of file".

The -M tells less to show a "long prompt", which in particular includes the percentage. But it seems man makes less include the percentage automatically, even if you leave -M out, if man detects a "recent version of less". See the -r prompt section of man man for more info.

From the man man (in 2013):

-P pager, --pager=pager
       Specify which output pager to use.  By default, man uses pager
       -s.  This option overrides the $MANPAGER environment variable,
       which in turn overrides the $PAGER environment  variable.   It
       is not used in conjunction with -f or -k.

       The value may be a simple command name or a command with argu‐
       ments, and may use shell quoting (backslashes, single  quotes,
       or  double  quotes).  It may not use pipes to connect multiple
       commands; if you need that, use a wrapper  script,  which  may
       take  the file to display either as an argument or on standard
       input.

Note that it says -s is the default option used with the pager by man. In 2022 I no longer see the -s mentioned here in man man, but I don't see any harm in leaving it in (it squashes consecutive blank lines).