Environment variables.

envs () describe the PAGER and TERM environment variable for cmdliner.

find ~search ~don't finds a suitable pager. This is (in order):

1. Ok None if don't is true or if the TERM environment variable is dumb or undefined.
2. Ok (Some pager) if pager is a tool invocation parsed from the PAGER environment variable that can be found via Os.Cmd.find_tool ?win_exe ?search.
3. Ok (Some pager) if either less or more can be found (in that order) via Os.Cmd.find_tool ?win_exe ?search.
4. Ok None otherwise.

page_stdout pager setups the program so that if pager is Some cmd, the standard output of the program is redirected to a spawn of cmd with the following twists:

• If the environment variable LESS is undefined in the current environment it is set to LESS=FRX for the spawn of cmd.
• A Stdlib.at_exit function is installed that flushes B0_std.Fmt.stdout and Stdlib.stdout, closes Unix.stdout and waits upon the cmd spawn termination.

If pager is None this function has no effect.

page_files pager fs uses pager to page the files fs. If pager is:

• None, each of the fs files is output on stdout in order separated by a file separator character (U+001C).
• Some cmd, cmd is run with fs as arguments. If fs is empty does nothing.

don't ~docs () is a --no-pager command line option to unconditionally request not use a pager. docs is the manual section where the option is documented, defaults to Cmdliner.Manpage.s_common_options.