.Dd December 5, 2016
.Dt VIS 1
.Os Vis VERSION
.
.Sh NAME
.Nm vis
.Nd a highly efficient text editor
.
.Sh SYNOPSIS
.Nm
.Op Fl v
.Op Ic +command
.Op Fl -
.Op Ar files ...
.
.Sh DESCRIPTION
.Nm
is a highly efficient screen-oriented text editor combining the strengths of both
.Nm vi(m)
and
.Nm sam .
.
This manual page is intended for users already familiar with
.Nm vi Ns / Ns Nm sam .
Anyone else should almost certainly read a good tutorial on
either editor before this manual page.
.
The following options are available:
.Bl -tag -width indent
.It Fl v
Print version information and exit.
.
.It Sy +command
Execute command after loading file.
.
.It Fl -
Denotes  the  end  of the options. Arguments after this will be handled as a
file name.
.\" TODO mention +command
.El
.Pp
The special file
.Cm -
instructs
.Nm
to read from standard input in which case
.Ic :wq
will write to standard output, thereby enabling usage as an interactive filter.
.Pp
If standard input is redirected and all input is consumed,
.Nm
will open /dev/tty to gather further commands. Failure to do so results in
program termination.
.
.Ss Modes
.Nm
employs the same
.Em modal
editing approach as
.Nm vi .
It supports a normal, operator pending, insert, replace and visual
(in both line and character wise variants) mode.
.\" TODO: add short per-mode descripton?
.Pp
The visual block and ex modes are deliberately not implemented,
instead
.Nm
has built in support for multiple cursors/selections and an
.Em interactive
variant of the structural regular expression based command language of
.Nm sam .
.
.Ss Undo/Redo
.Nm
uses an undo tree to keep track of text revisions. The
.Ic u
(undo) and
.Aq Ic C-r
(redo) commands can be used to traverse the tree along the main branch.
Additionally
.Ic g+
and
.Ic g-
traverse the history in chronological order. Furthermore the
.Ic :earlier
and
.Ic :later
commands provide means to restore the text to an arbitrary state.
.
.Ss Marks
A mark associates a given file position to a symbolic name.
A mark becomes invalid once the underlying file content changes (e.g. it
being deleted or replaced). If said changes are later undone the mark becomes
valid again.
.Bl -tag -width indent
.It a-z
general purpose marks
.It <
start of the last selected visual area in current file
.It >
end of the last selected visual area in current file
.El
.Pp
No marks across files are supported. Marks are not preserved over editing sessions.
.
.Ss Registers
Registers can hold arbitrary data which can later be re-inserted into
the file or executed as a macro. Supported registers include:
.Bl -tag -width indent
.It \(dqa-\(dqz
general purpose registers
.It \(dqA-\(dqZ
append to corresponding general purpose register
.It \(dq*, \(dq+
system clipboard integration via shell script
.Xr vis-clipboard 1
.It \(dq0
yank register, most recently yanked range
.It \(dq/
search register, most recently used search pattern
.It \(dq:
command register, most recently executed command
.It \(dq_
black hole (/dev/null) register, ignore content is always empty
.El
.Pp
If no explicit register is specified a default register is used.
.
.Ss Macros
.
The general purpose registers
.Cm \(dqa-\(dqz
can be used to record macros. Use
one of
.Cm \(dqA-\(dqZ
to append to an existing macro.
.Ic q
starts a recording,
.Ic @
plays it back.
.Ic @@
refers to the most recently recorded macro.
.Ic @:
repeats the last :-command.
.Ic @/
is equivalent to
.Ic n
in normal mode.
.
.Ss Jump list and Change list
.
A per window, fixed sized file local jump list (navigate with
.Aq Ic C-O
and
.Aq Ic C-I )
and change list (navigate with
.Ic g;
and
.Ic g, )
is supported.
.
.Ss Encoding, Tab and Newline handling
.
.Nm
always assumes the input file to be UTF-8 encoded. If you wish to edit
files with legacy encodings, use
.Xr iconv 1
to convert them as needed.
.Aq Tab
can optionally be expanded to a configurable number of spaces (see
.Sx "SET OPTIONS" ) .
The first line ending in the file determines what will be inserted when pressing
.Aq Enter
(defaults to \\n).
.
.Ss Mouse support
The mouse is currently not used at all.
.
.Sh SAM COMMANDS
.
.Nm
supports an interactive variant of the structural regular expression based command language introduced by
.Xr sam 1 .
.
.Ss Regular expressions
.Nm
currently defers regular expression matching to the underlying C library.
It uses what POSIX refers to as
.Dq Extended Regular Expressions
as described in
.Xr regex 7 "."
.
Additonally \[rs]n and \[rs]t may be used to refer to newlines and tabs, respectively.
The
.Cm "."
atom matches any character except newline.
.
The empty regular expression stands for the last complete expression encountered.
.
.Ss Addresses
An address identifies a substring (or range) in a file. In the following
.Do
character
.Sy n
.Dc
means the null string after the
.Sy n\fR-th
character in the file, with 1 the first character in the file.
.Do
Line
.Sy n
.Dc
means the
.Sy n\fR-th
match, starting at the beginning of the file, of the regular expression
.Li ".*\[rs]n?" .
.Pp
All windows always have at least one current substring which
is the default address. In sam this is referred to as
.Sy dot .
In
.Nm
multiple
.Dq dots
can exist at the same time.
In normal mode each cursor induces such a range, representing the
character it is currently over. Similarly, in visual mode each
selection serves as a default address.
.Ss Simple addresses
.Bl -tag -width indent
.It Ic #n
The empty string after character
.Sy n ;
.Li #0
is the beginning of the file.
.It Ic n
Line
.Sy n .
.It Ic /regexp/
.It Ic ?regexp?
The substring that matches the regular expression, found by looking
towards the end
.Pq Li /
or beginning
.Pq Li \&?
of the file. The search does not wrap around when hitting the end
.Pq start
of the file.
.It Ic 0
The string before the first full line.
This is not necessarily the null string; see
.Li +
and
.Li -
below.
.It Ic $
The null string at the end of the file.
.It Ic "."
Dot, the current range.
.It Ic "'m"
The mark
.Sy m
in the file.
.El
.
.Ss Compound addresses
In the following,
.Sy a1
and
.Sy a2
are addresses.
.Bl -tag -width indent
.It Sy a1+a2
The address
.Sy a2
evaluated starting at the end of
.Sy a1 .
.It Sy a1-a2
The address
.Sy a2
evaluated looking the reverse direction starting at the beginning of
.Sy a1 .
.It Sy "a1,a2"
The substring from the beginning of
.Sy a1
to the end of
.Sy a2 .
If
.Sy a1
is missing,
.Li 0
is substituted.
If
.Sy a2
is missing,
.Li $
is substituted.
.It Sy a1;a2
Like
.Dq Sy a1,a2
but with
.Sy a2
evaluated at the end of, and range set to,
.Sy a1 .
.El
.Pp
The operators
.Li +
and
.Li -
are high precedence, while
.Li ","
and
.Li ";"
are low precedence.
.Pp
In both
.Li +
and
.Li -
forms, if
.Sy a2
is a line or character address with a missing number, the number defaults to 1.
If
.Sy a1
is missing,
.Li "."
is substituted.
If both
.Sy a1
and
.Sy a2
are present and distinguishable,
.Li +
may be elided.
.Sy a2
may be a regular expression; if it is delimited by
.Dq Li \&?
characters, the effect of the
.Li +
or
.Li -
is reversed.
.
The
.Li %
sign is an alias for
.Li ","
and hence
.Li 0,$ .
.
It is an error for a compound address to represent a malformed substring.
.
.Ss Commands
In the following, text demarcated by slashes represents text delimited by any printable ASCII character except alphanumerics.
Any number of trailing delimiters may be elided, with multiple elisions then representing null strings, but the first delimiter must always be present.
In any delimited text, newline may not appear literally;
.Li \[rs]n
and
.Li \[rs]t
may be typed for newline and tab;
.Li \[rs]/
quotes the delimiter, here
.Li / .
Backslash is otherwise interpreted literally.
.Pp
Most commands may be prefixed with an address to indicate their range
of operation.  If a command takes an address and none is supplied, a
default address is used.  In normal mode this equates to the character
the cursor is currently over. If only one cursor exists
.Ic x
and
.Ic y
default to the whole file
.Li "0,$" .
In normal mode the write commands
.Ic w
and
.Ic wq
always apply to the whole file.
Commands are executed once for every cursor.
In visual mode the commands are applied to every selection
as if an implicit
.Ic x
command, matching the existing selections, was present.
.
.Pp
In the description,
.Dq range
is used to represent whatever address is supplied.
.Pp
If after a successful command execution no selections remain,
the editor will switch to normal mode, otherwise it remains in
visual mode. This allows
.Em interactive
refinements of ranges.
.
.\" Many commands set the value of dot as a side effect.
.\" If so, it is always to the
.\" .Dq result
.\" of the change: the empty string for a deletion, the new text for an insertion, etc.
.\" .Po
.\" but see the
.\" .Sy s
.\" and
.\" .Sy e
.\" commands
.\" .Pc "."
.Ss Text commands
.Bl -tag -width indent
.It Ic a/text/
Insert the text into the file after the range.
.\" Set dot.
.Pp
May also be written as
.Bd -literal -offset indent
 a
 lines
 of
 text
 .
.Ed
.It Ic c \fR or i
Same as
.Sy a ,
but
.Sy c
replaces the text, while
.Sy i
inserts
.Em before
the range.
.It Sy d
Delete the text in range.
.\" Set dot.
.It Sy s/regexp/text/
Substitute
.Sy text
for the first match of the regular expression in the range.
Currently implemented in terms of
.Xr sed 1 "."
.El
.
.Ss Display commands
.Bl -tag -width Ds
.It Ic p
Create a new selection for the range. If empty, create a new cursor.
.El
.
.Ss I/O commands
.Bl -tag -width indent
.It Ic e[!] Bq file name
Replace the file by the contents of the named external file.
If no file name is given, reload file from disk.
.It Ic r file name
Replace the text in the range by the contents of the named external file.
.\" Set dot.
.It Ic w[!] Bq file name
Write the range
.Po
default
.Li 0,$
.Pc
to the named external file.
.It Ic wq[!] Bq file name
Same as
.Ic w ,
but close file afterwards.
.El
.Pp
If the file name argument is absent from any of these, the current file name is used.
.Ic e
always sets the file name,
.Ic w
will do so if the file has no name.
Forcing the
.Ic e
command with
.Cm "!"
will discard any unsaved changes. Forcing
.Ic w
will overwrite the file on disk even if it has been externally modified
since loading it.  Write commands with a non-default addresses and no
file name are destructive and need always to be forced.
.Bl -tag -width indent
.It Ic "< shell-command"
Replace the range by the standard output of the shell command.
.It Ic "> shell-command"
Sends the range to the standard input of the shell command.
.It Ic "| shell-command"
Send the range to the standard input, and replace it by the standard output, of the shell command.
.It Ic "! shell-command"
Run interactive shell command, redirect keyboard input to it.
.It Ic "cd directory"
Change working directory.
If no directory is specified,
.Ev "$HOME"
is used.
.El
.Pp
In any of
.Ic "<" ,
.Ic ">" ,
.Ic "|" ,
or
.Ic "!" ,
if the shell command is omitted, the last shell command
.Pq "of any type"
is substituted.
.Ss Loops and conditionals
.Bl -tag -width indent
.It Ic x/regexp/ Bq command
For each match of the regular expression in the range, run the command with range set to the match.
If the regular expression and its slashes are omitted,
.Li "/.*\[rs]n/"
is assumed.
Null string matches potentially occur before every character of the range and at the end of the range.
.It Ic y/regexp/ Bq command
Like
.Ic x ,
but run the command for each substring that lies before, between, or after the matches that would be generated by
.Ic x .
There is no default behavior.
Null substrings potentially occur before every character in the range.
.It Ic "X/regexp/ command"
For each file whose file name matches the regular expression, make that the current file and run the command.
If the expression is omitted, the command is run in every file.
.It Ic "Y/regexp/ command"
Same as
.Ic X ,
but for files that do not match the regular expression, and the expression is required.
.It Ic "g/regexp/ command"
.It Ic "v/regexp/ command"
If the range contains
.Po
.Ic g
.Pc
or does not contain
.Po
.Ic v
.Pc
a match for the expression, run command on the range.
.El
.Pp
These may be nested arbitrarily deeply.
An empty command in an
.Ic x
or
.Ic y
defaults to
.Ic p .
.Ic X ,
.Ic Y ,
.Ic g
and
.Ic v
do not have defaults.
.
.Ss Grouping and multiple changes
Commands may be grouped by enclosing them in curly braces.
Semantically, the opening brace is like a command: it takes an
.Pq optional
address and runs each sub-command on the range.
Commands within the braces are executed sequentially, and changes made by one command are visible to other commands.
.
Braces may be nested arbitrarily.
.
.Sh VI(M) KEY BINDINGS
.
In the following sections angle brackets are used to denote special keys.
The prefixes
.Cm C- ,
.Cm S- ,
and
.Cm M-
are used to refer to the
.Aq Ctrl ,
.Aq Shift
and
.Aq Alt
modifiers, respectively.
.Pp
All active key bindings can be listed at runtime using the
.Cm :help
command.
.
.Ss Operators
.
Operators perform a certain operation an a text range indicated by either a
motion, a text object or an existing selection.
.
.Bl -tag -width indent
.It c
change, delete range and enter insert mode
.It d
delete range
.It !
filter range through external shell command
.It =
indent, currently an alias for gq
.It gq
format, filter range through
.Xr fmt 1
.It gu
make lowercase
.It gU
make uppercase
.It J
join lines, insert spaces in between
.It gJ
join lines remove any delimiting white spaces
.It p
put, insert register content
.It <
shift-left, decrease indent
.It >
shift-right, increase indent
.It ~
swap case
.It y
yank, copy range to register
.El
.Pp
Operators can be forced to work line wise by specifying
.Cm V .
.
.Ss Motions
.
.\" TODO? more formal definition: pos -> [min(pos, f(pos)), max(pos, f(pos))]
Motions take an initial file position and transform it to a destination file position,
thereby defining a range.
.\" TODO define word/WORD
.
.Bl -tag -width indent
.It 0
start of line
.
.It b
previous start of a word
.
.It B
previous start of a WORD
.
.It $
end of line
.
.It e
next end of a word
.
.It E
next end of a WORD
.
.It F Aq char
to next occurrence of char to the left
.
.It f Aq char
to next occurrence of char to the right
.
.It ^
first non-blank of line
.
.It g0
begin of display line
.
.It g$
end of display line
.
.It ge
previous end of a word
.
.It gE
previous end of a WORD
.
.It gg
begin of file
.
.It G
goto line or end of file
.
.It gj
display line down
.
.It gk
display line up
.
.It g_
last non-blank of line
.
.It gm
middle of display line
.
.It |
goto column
.
.It h
char left
.
.It H
goto top/home line of window
.
.It j
line down
.
.It k
line up
.
.It l
char right
.
.It L
goto bottom/last line of window
.
.It ` Aq mark
go to mark
.
.It ' Aq mark
go to start of line containing mark
.
.It %
match bracket
.
.It M
goto middle line of window
.
.It ]]
next end of C-like function
.
.It }
next paragraph
.
.It )
next sentence
.
.It ][
next start of C-like function
.
.It N
repeat last search backwards
.
.It n
repeat last search forward
.
.It []
previous end of C-like function
.
.It [{
previous start of block
.
.It ]}
next start of block
.
.It [(
previous start of parenthese pair
.
.It ])
next start of parenthese pair
.
.It {
previous paragraph
.
.It "("
previous sentence
.
.It [[
previous start of C-like function
.
.It ;
repeat last to/till movement
.
.It ,
repeat last to/till movement but in opposite direction
.
.It #
search word under cursor backwards
.
.It *
search word under cursor forwards
.
.It T Aq char
till before next occurrence of char to the left
.
.It t Aq char
till before next occurrence of char to the right
.
.It ? pattern
to next match of pattern in backward direction
.
.It / pattern
to next match of pattern in forward direction
.
.It w
next start of a word
.
.It W
next start of a WORD
.El
.
.Ss Text objects
.\" TODO? more formal definition: text-object: pos -> [a, b]
Text objects take an initial file position and transform it to a range
where the former does not necessarily have to be contained in the latter.
.
All of the following text objects are implemented in an inner variant
(prefixed with
.Cm i ")"
where the surrounding white space or delimiting characters are not part
of the resulting range and a normal variant (prefixed with
.Cm a ")"
where they are.
.Bl -tag -width indent
.
.It w
word
.
.It W
WORD
.
.It s
sentence
.
.It p
paragraph
.
.It [,], (,), {,}, <,>, \&", ', `
block enclosed by these symbols
.El
.Pp
Further available text objects include:
.Bl -tag -width indent
.
.It gn
matches the last used search term in forward direction
.
.It gN
matches the last used search term in backward direction
.
.It ae
entire file content
.
.It ie
entire file content except for leading and trailing empty lines
.
.It af
C-like function definition including immediately preceding comments
.
.It if
C-like function definition only function body
.
.It al
current line
.
.It il
current line without leading and trailing white spaces
.El
.
.Ss Multiple Cursors and Selections
.
.Nm
supports multiple cursors with immediate visual feedback. There always
exists one primary cursor located within the current view port. Additional
cursors can be created as needed. If more than one cursor exists,
the primary one is styled differently.
.Pp
To manipulate multiple cursors use in normal mode:
.Bl -tag -width indent
.It Aq C-k
create count new cursors on the lines above
.It Aq C-M-k
create count new cursors on the lines above the first cursor
.It Aq C-j
create count new cursors on the lines below
.It Aq C-M-j
create count new cursors on the lines below the last cursor
.It Aq C-p
remove primary cursor
.It Aq C-n
select word the cursor is currently over, switch to visual mode
.It Aq C-u
make the count previous cursor primary
.It Aq C-d
make the count next cursor primary
.It Aq C-c
remove the count cursor column
.It Aq C-l
remove all but the count cursor column
.It Aq Tab
try to align all cursor on the same column
.It Aq Escape
dispose all but the primary cursor
.El
.Pp
The visual modes were enhanced to recognize:
.Bl -tag -width indent
.It I
create a cursor at the start of every selected line
.It A
create a cursor at the end of every selected line
.It Aq Tab
left align selections by inserting spaces
.It Aq S-Tab
right align selections by inserting spaces
.It Aq C-n
create new cursor and select next word matching current selection
.It Aq C-x
clear (skip) current selection, but select next matching word
.It Aq C-p
remove primary cursor
.It Aq C-u
.It Aq C-k
make the count previous cursor primary
.It Aq C-d
.It Aq C-j
make the count next cursor primary
.It Aq C-c
remove the count cursor column
.It Aq C-l
remove all but the count cursor column
.It +
rotates selections rightwards count times
.It -
rotates selections leftwards count times
.It \e
trim selections, remove leading and trailing white space
.It Aq Escape
clear all selections, switch to normal mode
.El
.Pp
In insert and replace mode:
.Bl -tag -width indent
.
.It Aq S-Tab
align all cursors by inserting spaces
.El
.
.Sh VI(M) COMMANDS
.
Any unique prefix can be used to abbreviate a command.
.
.Ss File and Window management
.
A file must be opened in at least one window. If the last window displaying a
certain file is closed all unsaved changes are discarded. Windows are equally
sized and can be displayed in either horizontal or vertical fashion.
The
.Aq C-w
h,
.Aq C-w
j,
.Aq C-w
k and
.Aq C-w
l key mappings can be used to switch between windows.
.Bl -tag -width indent
.It Cm :new
open an empty window, arrange horizontally
.It Cm :vnew
open an empty window, arrange vertically
.It Cm :open[!] Bq file name
open a new window, displaying file name if given
.It Cm :split Bq file name
split window horizontally
.It Cm :vsplit Bq file name
split window vertically
.It Cm :bdelete[!]
close all windows which display the same file as the current one
.It Cm :q[!]
close currently focused window
.It Cm :qall[!]
close all windows, exit editor
.El
.Pp
Commands taking a file name will invoke the
.Xr vis-open 1
utility, if given a file pattern or directory.
.
.Ss Runtime key mappings
.Nm
supports global as well as window local run time key mappings which are
always evaluated recursively.
.
.Bl -tag -width indent
.It Cm :map[!] <mode> <lhs> <rhs>
add a global key mapping
.It Cm :map-window[!] <mode> <lhs> <rhs>
add a window local key mapping
.It Cm :unmap <mode> <lhs>
remove a global key mapping
.It Cm :unmap-window <mode> <lhs>
remove a window local key mapping
.El
In the above
.Cm <mode>
refers to one of
.Ql normal ,
.Ql insert ,
.Ql replace ,
.Ql visual ,
.Ql visual-line
or
.Ql operator-pending ;
.Cm <lhs>
refers to the key to map and
.Cm <rhs>
is a key action or alias. An existing mapping may be overridden by forcing
the map command by specifying
.Cm "!" .
.Pp
Because key mappings are always recursive, doing something like:
.Pp
.Dl :map! normal j 2j
.Pp
will not work because it would enter an endless loop. Instead,
.Nm
uses pseudo keys referred to as key actions which can be used to invoke
a set of available editor functions.
.Ic :help
lists all currently active key bindings as well as all available symbolic
keys.
.
.Ss Keyboard Layout Specific Mappings
.
In order to facilitate usage of non-latin keyboard layouts,
.Nm
allows to map locale specific keys to their latin equivalents by means of the
.Pp
.Dl :langmap <locale-keys> <latin->keys>
.Pp
command. As an example, the following maps the movement keys in Russian layout:
.Pp
.Dl :langmap ролд hjkl
.Pp
If the key sequences have not the same length, the remainder of the longer
sequence will be discarded.
.Pp
The defined mappings take effect
in all non-input modes, i.e. everywhere except in insert and replace mode.
.
.Ss Undo/Redo
.Bl -tag -width indent
.It Ic :earlier Bq count
revert to older text state
.It Ic :later Bq count
revert to newer text state
.El
.Pp
If count is suffixed by either of
.Sy d
.Pq days ,
.Sy h
.Pq hours ,
.Sy m
.Pq minutes
or
.Sy s
.Pq seconds
it is interpreted as an offset from the current system time and the closest
available text state is restored.
.
.Sh SET OPTIONS
There are a small number of options that may be set
.Pq or unset
to change the editor's behavior using the
.Cm :set
command.
This section describes the options, their abbreviations and their
default values.
.Pp
In each entry below, the first part of the tag line is the full name
of the option, followed by any equivalent abbreviations.
The part in square brackets is the default value of the option.
.Bl -tag -width indent
.It Cm shell Bq \&"/bin/sh\&"
User shell to use for external commands, overrides
.Cm $SHELL
and shell field of password database
.Cm /etc/passwd
.It Cm escdelay Bq 50
Milliseconds to wait before deciding whether an escape sequence should
be treated as an
.Aq Cm Escape
key.
.It Cm tabwidth , tw Bq 8
Display width of a tab and number of spaces to use if
.Cm expandtab
is enabled.
.It Cm autoindent , ai Bq off
Automatically indent new lines by copying white space from previous line.
.It Cm expandtab , et Bq off
Whether
.Aq Cm Tab
should be expanded to
.Cm tabwidth
spaces.
.It Cm number , nu Bq off
Display absolute line numbers.
.It Cm relativenumbers , rnu Bq off
Display relative line numbers.
.It Cm cursorline , cul Bq off
Highlight line primary cursor resides on.
.It Cm colorcolumn , cc Bq 0
Highlight a fixed column.
.It Cm horizon Bq 32768
How many bytes back the lexer will look to synchronize parsing.
.It Cm theme Bq \&"default-16\&" or \&"default-256\&"
Color theme to use, name without file extension.
.It Cm syntax Bq off
Syntax highlighting lexer to use, name without file extension.
.It Cm show-tabs Bq off
Whether to display replacement symbol instead of tabs.
.It Cm show-newlines Bq off
Whether to display replacement symbol instead of newlines.
.It Cm show-spaces Bq off
Whether to display replacement symbol instead of blank cells.
.It Cm savemethod Bq auto
How the current file should be saved,
.Sy atomic
which uses
.Xr rename 2
to atomically replace the file,
.Sy inplace
which truncates the file and then rewrites it or
.Sy auto
which tries the former before falling back to the latter. The rename
method fails for symlinks, hardlinks, in case of insufficient directory
permissions or when either the file owner, group, POSIX ACL or SELinux
labels can not be restored.
.El
.
.Sh CONFIGURATION
.
.Nm
uses Lua for configuration and scripting purposes.
During startup
.Pa visrc.lua
(see the
.Sx FILES
section) is sourced which can be used to set personal configuration
options. As an example the following will enable the display of line
numbers:
.Pp
.Dl vis:command('set number')
.
.Sh ENVIRONMENT
.Bl -tag -width indent
.It Ev VIS_PATH
The default path to use to load Lua support files.
.It Ev HOME
The home directory used for the
.Ic cd
command if no argument is given.
.It Ev TERM
The terminal type to use to initialize the curses interface, defaults to
.Sy xterm
if unset.
.It Ev SHELL
The command shell to use for I/O related commands like
.Ic "!" ,
.Ic ">" ,
.Ic "<"
and
.Ic "|" .
.It Ev XDG_CONFIG_HOME
The configuration directory to use, defaults to
.Pa $HOME/.config
if unset.
.El
.
.Sh ASYNCHRONOUS EVENTS
.Bl -tag -width indent
.It Dv SIGSTOP
Suspend editor.
.It Dv SIGCONT
Resume editor.
.It Dv SIGBUS
An
.Xr mmap 2
ed file got truncated, unsaved file contents will be lost.
.It Dv SIGHUP
.It Dv SIGTERM
Restore initial terminal state. Unsaved file contents will be lost.
.It Dv SIGINT
When an interrupt occurs while an external command is being run it is terminated.
.It Dv SIGWINCH
The screen is resized.
.El
.
.Sh FILES
Upon startup
.Nm
will source the first
.Pa visrc.lua
configuration file found from these locations:
.Bl -bullet
.It
.Pa $VIS_PATH
.It
The location of the
.Nm
binary (on systems where
.Pa /proc/self/exe
is available).
.It
.Pa $XDG_CONFIG_HOME/vis
where
.Pa $XDG_CONFIG_HOME
refers to
.Pa $HOME/.config
if unset.
.
.It
.Pa /usr/local/share/vis
or
.Pa /usr/share/vis
depending on the build configuration.
.El
.
.Sh EXIT STATUS
.Ex -std
.
.Sh EXAMPLES
Use
.Nm
as an interactive filter as used by
.Xr dvtm 1 :
.Pp
.Dl $ { echo Pick your number; seq 1 10; } | vis - > choice
.Pp
Use the
.Xr vis-open 1
based file browser to list all C language source files:
.Pp
.Dl :e *.c
.Pp
Spawn background process and pipe range to its standard input:
.Pp
.Dl :> { plumber <&3 3<&- & } 3<&0 1>&- 2>&-
.Sh SEE ALSO
.Xr vis-clipboard 1 ,
.Xr vis-complete 1 ,
.Xr vis-menu 1 ,
.Xr vis-open 1 ,
.Xr vi 1
and
.Xr sam 1
.Pp
.Lk http://doc.cat-v.org/bell_labs/sam_lang_tutorial/sam_tut.pdf "A Tutorial for the Sam Command Language"
by Rob Pike
.Pp
.Lk http://doc.cat-v.org/plan_9/4th_edition/papers/sam/ "The Text Editor sam"
by Rob Pike
.Pp
.Lk http://man.cat-v.org/plan_9/1/sam "Plan9 manual page for sam(1)"
.Pp
.Lk http://doc.cat-v.org/bell_labs/structural_regexps/se.pdf "Structural Regular Expressions"
by Rob Pike
.Pp
.Lk http://pubs.opengroup.org/onlinepubs/9699919799/utilities/vi.html "vi - screen-oriented (visual) display editor"
.St -p1003.1
.
.Sh STANDARDS
.Nm
does not strive to be
.St -p1003.1
compatible, but shares obvious similarities with the
.Nm vi
utility.
.
.\" .Sh HISTORY
.\" TODO something about vi(m) and sam history
.
.Sh AUTHORS
.Nm
is written by
.An Marc André Tanner Aq mat at brain-dump.org
.
.Sh BUGS
On some systems there already exists a
.Nm
binary, thus causing a name conflict.