NVI FAQ


Source:
https://sites.google.com/a/bostic.com/keithbostic/the-berkeley-vi-editor-home-page/nvi-faq


1. HOW CAN I GET VI TO DISPLAY MY CHARACTER SET?

Vi uses the C library routine isprint(3) to determine if a
character is printable, or should be displayed as an octal or
hexadecimal value on the screen.

Generally, if vi is displaying printable characters in
octal/hexadecimal forms, your environment is not configured
correctly.

Try looking at the man pages that allow you to configure your
locale.

For example, to configure an ISO 8859-1 locale under Solaris
using csh:

    setenv LANG C
    setenv LC_CTYPE iso_8859_1

If there is no other solution, you can use the print and
noprint edit options of vi to specify that a specific
character is printable or not printable.


2. MY MAP COMMANDS WON'T WORK

One thing that you should immediately check if a vi map
does not work is if it depends on the final cursor position
after a P or p command.

Historic vi implementations were inconsistent regarding
the final cursor position.

Vi follows the POSIX 1003.2 standard and always places the
cursor on the first character.


3. I'M USING KSH OR CSH AS MY VI EDIT OPTION SHELL VALUE,
   AND FILE EXPANSIONS DON'T WORK RIGHT

The problem may be in your shell startup files, such as:

    .cshrc

Vi executes the shell to perform name expansion, and the
shell generally reads its startup files.

If the startup files are not correctly configured for
non-interactive use, vi may be unable to parse the output.

For example, startup files that always echo prompts or
messages to the screen can break expansion handling.


4. HOW DOES THE ICLOWER EDIT OPTION DIFFER FROM
   THE IGNORECASE (IC) EDIT OPTION?

The ignorecase edit option always ignores the case of
letters in regular expressions.

The iclower edit option only ignores case if there are
no uppercase letters in the regular expression.

If any uppercase letter appears in the expression,
matching becomes case-sensitive.


5. WHEN I EDIT BINARY FILES, VI APPENDS A <NEWLINE>
   TO THE LAST LINE

This is historic vi behavior and is required by the
POSIX 1003.2 standard.

Future versions were expected to provide an option
to disable this behavior.


6. MY CURSOR KEYS DON'T WORK WHEN I'M IN TEXT INPUT MODE

A common problem over slow links is that the characters
generated by cursor keys do not arrive close enough together
for vi to interpret them as a single escape sequence.

Try increasing the value of the escapetime edit option.

This causes vi to wait longer before deciding that an
escape sequence has ended.


7. WHEN I EDIT SOME FILES, VI SEEMS TO HANG FOREVER

Vi uses flock(2) and fcntl(2) for file locking.

When editing files on NFS-mounted filesystems, lock
operations may hang for a very long time.

Turning off the lock edit option prevents vi from
attempting to acquire locks on edited files.


8. WHEN I COMPILE VI I GET LOTS OF WARNINGS ABOUT
   POINTER ASSIGNMENTS BEING INCOMPATIBLE

Vi is partially written to support wide characters.

Some interfaces still mix wide-character and non-wide-character
code, causing pointer type mismatches during compilation.


9. I GET JUMPY SCROLLING BEHAVIOR IN THE SCREEN

This is usually caused by broken or incomplete
terminfo/termcap entries.

If scrolling region capabilities are missing or incorrect,
screen updates may appear unstable.

Historic vi implementations often avoided this problem
because they implemented their own screen handling
instead of using curses libraries.

The recommended solution is to install a proper
terminfo or termcap entry for the terminal.


10. THE ENTIRE SCREEN REPAINTS ON EVERY KEYSTROKE

Your system curses implementation is likely broken.

Use the curses implementation provided with vi or
use an alternative implementation such as ncurses.


11. WHEN I USE VI ON A SUN CONSOLE (SUN-34)
    THE SCREEN IS OCCASIONALLY TRASHED

The Sun console cannot properly handle the 'al'
(insert line) terminal capability.

Removing the problematic capability from the
terminfo/termcap entry fixes the issue.


12. I DON'T HAVE A VERSION OF CTAGS
    (OR IT DOESN'T TAG ENOUGH THINGS)

The FAQ references multiple ctags implementations,
including Exuberant Ctags.

Exuberant Ctags supported:

    - macro definitions
    - enumerated values
    - functions and methods
    - struct/union/enum tags
    - typedefs
    - variable declarations

and more.


13. WHEN I UPDATE A FILE I ALREADY HAVE OPEN,
    AND USE :e TO REREAD IT, I GET NULS

The system mmap(2) implementation likely contains a bug.

The workaround is to exit vi and reopen the file.


14. WHERE CAN I GET CSCOPE?

The FAQ references commercial UNIX versions and
an Open Source version of cscope.

Open Source cscope:
http://cscope.sourceforge.net/


15. THE WORD BOUNDARY MATCHING IN REGULAR
    EXPRESSIONS ISN'T WORKING

Make sure you are using the regular expression
package supplied with nvi.

Word boundary matching was an extension to the
POSIX 1003.2 regular expression standard and
many vendor implementations did not support it.


NOTES

This FAQ reflects classic Unix and BSD engineering
practices from the 1990s.

Many topics remain relevant today, including:

    - locale configuration
    - UTF-8 handling
    - terminal descriptions
    - curses behavior
    - shell startup scripts
    - NFS locking
    - regular expression portability
    - screen repaint issues

The document also provides historical insight into
traditional vi behavior and portability concerns.


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Last Modified: 2026-05-09 23:46:00 UTC