elvis.9

操作系统设计与实现源码

   new file.

charattr
   Many text formatting programs allow you to designate portions of your
   text  to  be  underlined,  italicized,  or  boldface by embedding the
   special strings \fU, \fI, and \fB in your text.  The  special  string
   \fR marks the end of underlined or boldface text.

   Elvis normally treats those special strings just like any other text.
   However,  if  the  charattr  option  is on, then elvis will interpret
   those special strings correctly, to display  underlined  or  boldface
   text  on  the  screen.  (This only works, of course, if your terminal
   can display underlined and boldface, and if the  TERMCAP  entry  says
   how to do it.)

columns
   This is a 'read only' option.  You cannot change its value,  but  you
   can have elvis print it.  It shows how wide your screen is.

directory
   Elvis uses temporary files to store changed text.  This option allows
   you  to  control  where  those temporary files will be.  Ideally, you
   should store them on in fast non-volatile  memory,  such  as  a  hard
   disk.

   This option can only be set in the ".exrc" file.

errorbells
   Normally, elvis will ring your terminal's bell if you make an  error.
   However, in noerrorbells mode, your terminal will remain silent.

exrefresh
   The EX mode of elvis writes many lines to the screen.  You  can  make
   elvis  either  write  each  line to the screen separately, or save up


                                                                        



                                                                        


   many lines and write them all at once.

   The exrefresh option is normally on, so each line is written  to  the
   screen separately.

   You may wish to turn the exrefresh  option  off  (:se  noer)  if  the
   'write'  system  call is costly on your machine, or if you're using a
   windowing environment.  (Windowing environments  scroll  text  a  lot
   faster when you write many lines at once.)

   This option has no effect in vi mode.

ignorecase
   Normally, when elvis searches for text, it treats  uppercase  letters
   as being different for lowercase letters.

   When the ignorecase option is on, uppercase and lowercase are treated
   as equal.

keytime
   The arrow keys of most terminals send a multi-character sequence.  It
   takes  a  measurable  amount  of  time  for  these  sequences  to  be
   transmitted.  The keytime option allows you to  control  the  maximum
   amount  of time to allow for an arrow key (or other mapped key) to be
   received in full.

   The default keytime value is 2.  Because of the way UNIX  timekeeping
   works,  the  actual amount of time allowed will vary slightly, but it
   will always be between 1 and 2 seconds.

   If you set keytime to 1, then the actual amount of time allowed  will
   be  between  0 and 1 second.  This will generally make the keyboard's
   response be a little faster (mostly for the ESC key),  but  on  those
   occasions  where  the  time  allowed happens to be closer to 0 than 1
   second, elvis may fail to  allow  enough  time  for  an  arrow  key's
   sequence to be received fully.  Ugh.

   As a special case, you can set keytime to  0  to  disable  this  time
   limit  stuff  altogether.   The  big  problem here is:  If your arrow
   keys' sequences start with an ESC, then every time you hit  your  ESC
   key  elvis will wait... and wait... to see if maybe that ESC was part
   of an arrow key's sequence.

   NOTE: this option is a generalization of the timeout  option  of  the
   real vi.

keywordprg
   Elvis has a special keyword lookup feature.  You move the cursor onto
   a  word,  and  hit shift-K, and elvis uses another program to look up
   the word and display information about it.


                                                                        



                                                                        


   This option says which program gets run.  It should contain the  full
   pathname of the program; your whole execution path is not checked.

   The default value of this option is /usr/bin/ref, which is a  program
   that  looks  up  the  definition of a function in C.  It looks up the
   function name in a file called 'refs' which is created by ctags.

   You can substitute other programs,  such  as  an  English  dictionary
   program  or  the  online  manual.   elvis runs the program, using the
   keyword as its only argument.  The program should  write  information
   to  stdout.   The  program's exit status should be 0, unless you want
   elvis to print '<<< failed >>>".

lines
   This 'read only' option shows how many lines you screen has.

list
   Normally (in 'nolist" mode) elvis will  expand  tabs  to  the  proper
   number  of  spaces  on  the screen, so that the file appears the same
   would it would be if you printed it or looked at it with more.

   Sometimes, though, it can be handy to  have  the  tabs  displayed  as
   '^I".  In 'list" mode, elvis does this, and also displays a '$" after
   the end of the line.

magic
   The search mechanism in  elvis  can  accept  'regular  expressions'--
   --strings  in  which  certain  characters  have special meaning.  The
   magic option is normally on, which  causes  these  characters  to  be
   treated specially.  If you turn the magic option off (:se noma), then
   all characters except ^ and $ are treated literally.   ^ and $ retain
   their special meanings regardless of the setting of magic.

paragraphs
   The {  and  }  commands  move  the  cursor  forward  or  backward  in
   increments  of  one  paragraph.  Paragraphs may be separated by blank
   lines, or by a 'dot' command of a  text  formatter.   Different  text
   formatters  use  different 'dot' commands.  This option allows you to
   configure elvis to work with your text formatter.

   It is assumed that your formatter uses commands that start with a ".'
   character  at  the  front  of  a  line,  and then have a one- or two-
   character command name.

   The value of the paragraphs option is a string in which each pair  of
   characters  is  one  possible form of your text formatter's paragraph
   command.

readonly
   Normally, elvis will let you write back any file to  which  you  have


                                                                        



                                                                        


   write permission.  If you do not have write permission, then you  can
   only write the changed version of the file to a different file.

   If you set the readonly option, then elvis will pretend  you  do  not
   have  write  permission  to any file you edit.  It is useful when you
   really only mean to use elvis to look at a file, not  to  change  it.
   This way you cannot change it accidentally.

   This option is normally off, unless  you  use  the  'view'  alias  of
   elvis.  'View' is like vi except that the readonly option is on.

report
   Commands in elvis may affect many lines.  For commands that affect  a
   lot  of  lines,  elvis will output a message saying what was done and
   how many lines were affected.  This option allows you to define  what
   'a  lot  of  lines'  means.   The  default is 5, so any command which
   affects 5 or more lines will cause a message to be shown.

scroll
   The CTRL-U and CTRL-D keys normally scroll  backward  or  forward  by
   half  a  screenful, but this is adjustable.  The value of this option
   says how many lines those keys should scroll by.

sections
   The [[ and ]]  commands  move  the  cursor  backward  or  forward  in
   increment  of  1 section.  Sections may be delimited by a { character
   in column 1 (which is useful for C source code) or by means of a text
   formatter's 'dot' commands.

   This option allows you to configure elvis  to  work  with  your  text
   formatter's  'section'  command,  in  exactly  the  same way that the
   paragraphs option makes it work  with  the  formatter's  'paragraphs"
   command.

shell
   When elvis forks a shell (perhaps for the :! or :shell commands) this
   is  the program that is uses as a shell.  This is /bin/sh by default,
   unless you have set the SHELL environment variable, it which case the
   default value is copied from the environment.

shiftwidth
   The < and > commands shift text left or right by some uniform  number
   of  columns.  The shiftwidth option defines that uniform number.  The
   default is 8.

sidescroll
   For long lines, elvis scrolls sideways.  (This is different from  the
   real  vi,  which  wraps  a  single long line onto several rows of the
   screen.)  To minimize the number of scrolls needed, elvis  moves  the
   screen  sideways  by several characters at a time.  The value of this


                                                                        



                                                                        


   option says  how  many  characters'  widths  to  scroll  at  a  time.
   Generally, the faster your screen can be redrawn, the lower the value
   you will want in this option.

sync
   If the system crashes during an edit session, then most of your  work
   can  be  recovered  from  the temporary file that elvis uses to store
   changes.  However, sometimes MINIX will not copy changes to the  hard
   disk  immediately,  so  recovery might not be possible.  The [no]sync
   option lets you control this.  In nosync mode (which is the default),
   elvis  lets  the operating system control when data is written to the
   disk.  This is generally faster.  In  sync  mode,  elvis  forces  all
   changes  out to disk every time you make a change.  This is generally
   safer, but slower.

tabstop
   Tab characters are normally 8 characters wide,  but  you  can  change
   their widths by means of this option.

term
   This 'read only' option shows the name  of  the  termcap  entry  that
   elvis is using for your terminal.

vbell
   If your termcap entry describes a visible alternative to ringing your
   terminal's  bell,  then  this  option  will  say  whether the visible
   version gets used or not.  Normally it will be.

   If your termcap does NOT include a visible bell capability, then  the
   vbell option will be off, and you cannot turn it on.

warn
   Elvis will normally warn you if  you  run  a  shell  command  without
   saving  your changed version of a file.  The 'nowarn" option prevents
   this warning.

wrapmargin
   Normally (with wrapmargin=0) elvis will let  you  type  in  extremely
   long  lines,  if you wish.  However, with wrapmargin set to something
   other that 0 (wrapmargin=65 is nice), elvis will automatically  cause
   long  lines  to  be  'wrapped"  on a word break for lines longer than
   wrapmargin's setting.

wrapscan
   Normally, when you search for something, elvis will find it no matter
   where  it  is  in the file.  elvis starts at the cursor position, and
   searches forward.  If elvis hits  EOF  without  finding  what  you're
   looking for, then it wraps around to continue searching from line 1.

   If you turn off the wrapscan option (:se nows), then when elvis  hits


                                                                        



                                                                        


   EOF during a search, it will stop and say so.

Cflags

     Elvis uses many preprocessor symbols to control compilation.   Most
of  these  flags  allow you to disable small sets of features.  MINIX-ST
users will probably want all features enabled, but MINIX-PC  users  will
have to disable one or two feature sets because otherwise elvis would be
too large to compile and run.

These symbols can be defined via flags passed to the compiler.  The best
way  to  do  this  is  to  edit the Makefile, and append the flag to the
'CFLAGS=' line.  After you do that, you must recompile elvis  completely
by saying

        make  clean
        make

-DM_SYSV
   This flag causes elvis to use System-V ioctl() calls for  controlling
   your terminal; normally it uses v7/BSD/MINIX ioctl() calls.

-DDATE
   The symbol DATE should be defined to look  like  a  string  constant,
   giving  the  date  when elvis was compiled.  This date is reported by
   the ':version' command.

   You can also leave DATE undefined, in which case ':version' will  not
   report the compilation date.

-DCRUNCH
   This flag causes several large often-used macros to  be  replaced  by
   equivalent  functions.   This  saves about 4K of space in the '.text'
   segment, and it does not cost you any features.

-DDEBUG
   This adds many internal  consistency  checks  and  the  ':debug'  and
   ':validate'  commands.   It  increases the size of 'text' by about 5K
   bytes.

-DNO_CHARATTR
   This permanenently disables the 'charattr' option.   It  reduces  the
   size of '.text' by about 850 bytes.

-DNO_RECYCLE
   Normally, elvis will  recycle  space  in  the  temporary  file  which
   contains  totally  obsolete  text.   The -DNO_RECYCLE option disables
   this, making your '.text'  segment  smaller  by  about  1K  but  also
   permitting the temporary file to grow very quickly.  If you have less
   than two megabytes of free space on  your  disk,  then  do  not  even


                                                                        



                                                                        


   consider using this flag.

-DNO_SENTENCE
   This leaves out the '(' and ')' visual commands, and removes the code
   that  allows the '[[', ']]', '{', and '}' commands to recognize nroff
   macros.  The '[[' and ']]' commands will still move to the  start  of
   the  previous/next  C  function  source code, though, and '{' and '}'
   will move to the previous/next blank  line.   This  saves  about  650
   bytes from the '.text' segment.

-DNO_CHARSEARCH
   This leaves out the visual commands which locate a given character in
   the current line: 'f', 't', 'F', 'T', ';', and ','.  This saves about
   900 bytes.

-DNO_EXTENSIONS
   This leaves out the ':mkexrc' command, and the  'K'  and  '#'  visual
   commands.   Other  extensions  are  either  inherent in the design of
   elvis, or are too tiny to be worth removing.  This  saves  about  500
   bytes.

-DNO_MAGIC
   This permanently disables the 'magic'  option,  so  that  most  meta-
   characters  in  a  regular  expression are not recognized. This saves
   about 3K bytes from the '.text' segment.


Termcap Elvis can use standard termcap entries, but it  also  recognizes
and uses several extra capabilities, if you give them.  All of these are
optional.

   Capability        Description
   :PU=:             sequence received from the <PgUp> key
   :PD=:             sequence received from the <PgDn> key
   :HM=:             sequence received from the <Home> key
   :EN=:             sequence received from the <End> key
   :VB=:             sequence sent to start bold printing
   :Vb=:             sequence sent to end bold printing

Author

     Elvis was written by Steve Kirkendall.  He can be reached by  email
at: [e-mail] for comments regarding elvis.