Native Language System support (+)


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Native Language System support (+)
The shell is eight bit clean
(if so compiled; see the version shell variable)
and thus supports character sets needing this capability.
NLS support differs depending on whether or not
the shell was compiled to use the system's NLS (again, see version).
In either case, 7-bit ASCII is the default for character classification
(e.g. which characters are printable) and sorting,
and changing the LANG or LC_CTYPE environment variables
causes a check for possible changes in these respects.

When using the system's NLS, the setlocale(3) function is called
to determine appropriate character classification and sorting.
This function typically examines the LANG and LC_CTYPE
environment variables; refer to the system documentation for further details.
When not using the system's NLS, the shell simulates it by assuming that the
ISO 8859-1 character set is used
whenever either of the LANG and LC_CTYPE variables are set, regardless of
their values. Sorting is not affected for the simulated NLS.

In addition, with both real and simulated NLS, all printable
characters in the range \200-\377, i.e. those that have
M-char bindings, are automatically rebound to self-insert-command.
The corresponding binding for the escape-char sequence, if any, is
left alone.
These characters are not rebound if the NOREBIND environment variable
is set. This may be useful for the simulated NLS or a primitive real NLS
which assumes full ISO 8859-1. Otherwise, all M-char bindings in the
range \240-\377 are effectively undone.
Explicitly rebinding the relevant keys with bindkey
is of course still possible.

Unknown characters (i.e. those that are neither printable nor control
characters) are printed in the format \nnn.
If the tty is not in 8 bit mode, other 8 bit characters are printed by
converting them to ASCII and using standout mode. The shell
never changes the 7/8 bit mode of the tty and tracks user-initiated
changes of 7/8 bit mode. NLS users (or, for that matter, those who want to
use a meta key) may need to explicitly set
the tty in 8 bit mode through the appropriate stty(1)
command in, e.g., the ~/.login file.

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