envs describe the PAGER and TERM environment variable.

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.

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 ?search.
3. Ok (Some pager) if either less or more can be found (in that order) via Os.Cmd.find ?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 Pervasive.at_exit function is installed that flushes Fmt.stdout and 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.