lesspagerterminal
In modern web browsers and other software with text content, Space scrolls down more or less a screenful. ShiftSpace scrolls up in everything but less.
How can one use ShiftSpace to scroll up in less? Or alternatively, is there another pager (POSIX compatibility is my only requirement) that could do the job?
I was told some terminal emulators, and some terminal UI libraries (ncurses?), don't recognize ShiftSpace. Is that a valid issue?
There is a solution using Vim.
First, you need a Vim macro, which will do most of the work. Save it in ~/.vim/plugin/less.vim:
" :Less
" turn vim into a pager for psql aligned results
fun! Less()
set nocompatible
set nowrap
set scrollopt=hor
set scrollbind
set number
execute 'above split'
" resize upper window to one line; two lines are not needed because vim adds separating line
execute 'resize 1'
" switch to lower window and scroll 2 lines down
wincmd j
execute 'norm! 2^E'
" hide statusline in lower window
set laststatus=0
" hide contents of upper statusline. editor note: do not remove trailing spaces in next line!
set statusline=\
" arrows do scrolling instead of moving
nmap ^[OC zL
nmap ^[OB ^E
nmap ^[OD zH
nmap ^[OA ^Y
nmap <Space> <PageDown>
" faster quit (I tend to forget about the upper panel)
nmap q :qa^M
nmap Q :qa^M
endfun
command! -nargs=0 Less call Less()
Second, to emulate a pager, you need to invoke vim so that it will:
I put this together as helper script in ~/bin/vimpager:
#!/bin/bash
what=-
test "$@" && what="$@"
exec vim -u NONE -R -S ~/.vim/plugin/less.vim -c Less $what
Make the script executable with chmod +x ~/bin/vimpager.
Third, you need to override pager program for psql. Do not set variable PAGER globally, as it can affect other programs, not only psql. Instead, add this to your ~/.psqlrc file:
\setenv PAGER ~/bin/vimpager
Voila! After reloading your profile, you can enjoy the result, which should behave as expected (arrow keys browse both vertically and horizontally) and look like this: 
. Plus, all the power of Vim is right there if you need it.
less can follow by file nameThe feature has a fairly obscure syntax:
less --follow-name +F file.log
With less, --follow-name is different from the tail option --follow=name.
It does not make less follow the file, instead it modifies the behaviour of the command key F inside of less to follow based on the file name, not the file descriptor.
Also, there is no normal option to start less in follow mode.
But you can use the command line to give keystrokes to execute after startup, by prefixing them with +.
Combining the modifier option with +F, less will actually start in the (modified) follow mode.
Use +F alone for the equivalent of plain tail -f:
less +F file.log
Best Answer
I think you've brought up a culture clash caused by a technical limitation. Since Shift+Space generates the same output as Space, the Unix terminal model treats them identically. To distinguish between the two, you need a programming environment that supports key up / key down events. That is possible in X11 and in terminal emulators that support remapping keys. An example of remapping Shift+Space to PageUp: