termcap.5

Unix操作系统minix 2.0源码

     ul    bool         Underline character overstrikes
     UP    str   (NP*)  Move cursor up n lines
     up    str          Upline (cursor up)
     us    str          Start underscore mode
     vb    str          Visible bell (must not move cursor)
     ve    str          Make cursor appear normal (undo vs/vi)
     vi    str          Make cursor invisible
     vs    str          Make cursor very visible
     vt    num          Virtual terminal number (not supported on all systems)
     wi    str   (N)    Set current window
     ws    num          Number of columns in status line
     xb    bool         Beehive (f1=ESC, f2=^C)
     xn    bool         Newline ignored after 80 cols (Concept)
     xo    bool         Terminal uses xoff/xon (DC3/DC1) handshaking
     xr    bool  (o)    Return acts like ce cr nl (Delta Data)
     xs    bool         Standout not erased by overwriting (Hewlett-Packard)
     xt    bool         Tabs ruin, magic so char (Teleray 1061)
     xx    bool  (o)    Tektronix 4025 insert-line

     A Sample Entry

     The following entry, which describes the Concept-100, is among  the  more
     complex entries in the termcap file as of this writing.




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     ca|concept100|c100|concept|c104|concept100-4p|HDS Concept-100:\
       :al=3*\E^R:am:bl=^G:cd=16*\E^C:ce=16\E^U:cl=2*^L:cm=\Ea%+ %+ :\
       :co#80:.cr=9^M:db:dc=16\E^A:dl=3*\E^B:do=^J:ei=\E\200:eo:im=\E^P:in:\
       :ip=16*:is=\EU\Ef\E7\E5\E8\El\ENH\EK\E\200\Eo&\200\Eo\47\E:k1=\E5:\
       :k2=\E6:k3=\E7:kb=^h:kd=\E<:ke=\Ex:kh=\E?:kl=\E>:kr=\E=:ks=\EX:\
       :ku=\E;:le=^H:li#24:mb=\EC:me=\EN\200:mh=\EE:mi:mk=\EH:mp=\EI:\
       :mr=\ED:nd=\E=:pb#9600:rp=0.2*\Er%.%+ :se=\Ed\Ee:sf=^J:so=\EE\ED:\
       :.ta=8\t:te=\Ev    \200\200\200\200\200\200\Ep\r\n:\
       :ti=\EU\Ev  8p\Ep\r:ue=\Eg:ul:up=\E;:us=\EG:\
       :vb=\Ek\200\200\200\200\200\200\200\200\200\200\200\200\200\200\EK:\
       :ve=\Ew:vs=\EW:vt#8:xn:\
       :bs:cr=^M:dC#9:dT#8:nl=^J:ta=^I:pt:

     Entries may continue onto multiple lines  by  giving  a  \  as  the  last
     character  of  a  line,  and empty fields may be included for readability
     (here between the last field on a line and the first field on the  next).
     Comments may be included on lines beginning with "#".

     Types of Capabilities

     Capabilities in termcap are of three types: Boolean  capabilities,  which
     indicate particular features that the terminal has; numeric capabilities,
     giving the size of the display or  the  size  of  other  attributes;  and
     string  capabilities,  which give character sequences that can be used to
     perform particular terminal operations.  All capabilities have two-letter
     codes.   For  instance,  the  fact that the Concept has automatic margins
     (i.e., an automatic return and  linefeed  when  the  end  of  a  line  is
     reached)   is   indicated  by  the  Boolean  capability  am.   Hence  the
     description of the Concept includes am.

     Numeric capabilities are followed by the character `#'  then  the  value.
     In  the  example  above  co,  which  indicates  the number of columns the
     display has, gives the value `80' for the Concept.

     Finally, string-valued capabilities,  such  as  ce  (clear-to-end-of-line
     sequence)  are given by the two-letter code, an `=', then a string ending
     at the next following `:'.  A delay in milliseconds may appear after  the
     `='  in such a capability, which causes padding characters to be supplied
     by tputs after the remainder of the string is sent to provide this delay.
     The  delay  can be either a number, e.g. `20', or a number followed by an
     `*',  i.e.,  `3*'.   An  `*'  indicates  that  the  padding  required  is
     proportional  to  the  number of lines affected by the operation, and the
     amount given is the per-affected-line padding required.  (In the case  of
     insert-character,  the factor is still the number of lines affected; this
     is always 1 unless the terminal has in and the software uses  it.)   When
     an  `*'  is specified, it is sometimes useful to give a delay of the form
     `3.5' to specify a delay per line to tenths of milliseconds.   (Only  one
     decimal place is allowed.)




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     A  number  of  escape  sequences  are  provided  in   the   string-valued
     capabilities  for  easy encoding of control characters there.  \E maps to
     an ESC character, ^X maps to a control-X for any appropriate X,  and  the
     sequences  \n  \r  \t  \b \f map to linefeed, return, tab, backspace, and
     formfeed, respectively.  Finally, characters may be given as three  octal
     digits  after  a \, and the characters ^ and \ may be given as \^ and \\.
     If it is necessary to place a : in a capability it  must  be  escaped  in
     octal  as  \072.  If it is necessary to place a NUL character in a string
     capability it must be encoded as \200.   (The  routines  that  deal  with
     termcap use C strings and strip the high bits of the output very late, so
     that a \200 comes out as a \000 would.)

     Sometimes individual capabilities must be commented out.  To do this, put
     a  period  before the capability name.  For example, see the first cr and
     ta in the example above.

     Preparing Descriptions

     We now outline how  to  prepare  descriptions  of  terminals.   The  most
     effective  way  to  prepare  a  terminal  description is by imitating the
     description  of  a  similar  terminal  in  termcap  and  to  build  up  a
     description  gradually,  using partial descriptions with vi to check that
     they are correct.  Be aware that  a  very  unusual  terminal  may  expose
     deficiencies in the ability of the termcap file to describe it or bugs in
     vi.   To  easily  test  a  new  terminal  description  you  can  set  the
     environment   variable  TERMCAP  to  the  absolute  pathname  of  a  file
     containing the description you are working  on  and  programs  will  look
     there  rather  than  in  /etc/termcap.   TERMCAP  can  also be set to the
     termcap entry itself to  avoid  reading  the  file  when  starting  up  a
     program.

     To get the padding for insert-line right (if  the  terminal  manufacturer
     did  not  document it), a severe test is to use vi to edit /etc/passwd at
     9600 baud, delete roughly 16 lines from the middle of  the  screen,  then
     hit  the  `u'  key several times quickly.  If the display messes up, more
     padding is usually needed.  A  similar  test  can  be  used  for  insert-
     character.

     Basic Capabilities

     The number of columns on each line of the display  is  given  by  the  co
     numeric capability.  If the display is a CRT, then the number of lines on
     the screen is given by the li capability.  If the display wraps around to
     the  beginning of the next line when the cursor reaches the right margin,
     then it should have the am capability.  If the  terminal  can  clear  its
     screen, the code to do this is given by the cl string capability.  If the
     terminal overstrikes (rather than clearing the position when a  character
     is  overwritten), it should have the os capability.  If the terminal is a
     printing terminal, with no soft copy unit, give it both hc and  os.   (os
     applies to storage scope terminals, such as the Tektronix 4010 series, as


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     well as to hard copy and APL terminals.)  If there is a code to move  the
     cursor  to  the left edge of the current row, give this as cr.  (Normally
     this will be carriage-return, ^M.)  If there is  a  code  to  produce  an
     audible signal (bell, beep, etc.), give this as bl.

     If there is a code (such as backspace) to move the cursor one position to
     the  left,  that  capability  should be given as le.  Similarly, codes to
     move to the right, up, and down should  be  given  as  nd,  up,  and  do,
     respectively.   These local cursor motions should not alter the text they
     pass over; for example, you would not  normally  use  "nd= "  unless  the
     terminal  has  the  os  capability,  because  the  space  would erase the
     character moved over.

     A very important point here is that the local cursor motions  encoded  in
     termcap  have  undefined  behavior  at  the  left  and top edges of a CRT
     display.  Programs should never attempt  to  backspace  around  the  left
     edge,  unless  bw  is given, and never attempt to go up off the top using
     local cursor motions.

     In order to scroll text up, a program goes to the bottom left  corner  of
     the  screen  and  sends  the  sf  (index) string.  To scroll text down, a
     program goes to the top left corner  of  the  screen  and  sends  the  sr
     (reverse  index)  string.   The strings sf and sr have undefined behavior
     when not on  their  respective  corners  of  the  screen.   Parameterized
     versions  of  the  scrolling sequences are SF and SR, which have the same
     semantics as sf and sr except that they take  one  parameter  and  scroll
     that  many  lines.   They  also  have  undefined  behavior  except at the
     appropriate corner of the screen.

     The am capability tells whether the cursor sticks at the  right  edge  of
     the screen when text is output there, but this does not necessarily apply
     to nd from the last column.  Leftward local motion is  defined  from  the
     left  edge only when bw is given; then an le from the left edge will move
     to the right edge of the previous row.  This is useful for drawing a  box
     around  the edge of the screen, for example.  If the terminal has switch-
     selectable automatic margins, the  termcap  description  usually  assumes
     that  this  feature  is on, i.e., am.  If the terminal has a command that
     moves to the first column of the next line, that command can be given  as
     nw  (newline).   It is permissible for this to clear the remainder of the
     current line, so if the terminal has no correctly-working CR  and  LF  it
     may still be possible to craft a working nw out of one or both of them.

     These  capabilities  suffice  to  describe   hardcopy   and   "glass-tty"
     terminals.  Thus the Teletype model 33 is described as

       T3|tty33|33|tty|Teletype model 33:\
         :bl=^G:co#72:cr=^M:do=^J:hc:os:





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     and the Lear Siegler ADM-3 is described as

       l3|adm3|3|LSI ADM-3:\
         :am:bl=^G:cl=^Z:co#80:cr=^M:do=^J:le=^H:li#24:sf=^J:

     Parameterized Strings

     Cursor addressing and other strings requiring parameters are described by
     a  parameterized string capability, with printf(3)-like escapes %x in it,
     while other characters are passed through  unchanged.   For  example,  to
     address  the cursor the cm capability is given, using two parameters: the
     row and column to move to.  (Rows and columns are numbered from zero  and
     refer  to  the  physical  screen  visible  to the user, not to any unseen
     memory.  If the terminal has memory-relative cursor addressing, that  can
     be indicated by an analogous CM capability.)

     The % encodings have the following meanings:

             %%      output `%'
             %d      output value as in printf %d
             %2      output value as in printf %2d
             %3      output value as in printf %3d
             %.      output value as in printf %c
             %+x     add x to value, then do %.
             %>xy    if value > x then add y, no output
             %r      reverse order of two parameters, no output
             %i      increment by one, no output
             %n      exclusive-or all parameters with 0140 (Datamedia 2500)
             %B      BCD (16*(value/10)) + (value%10), no output
             %D      Reverse coding (value - 2*(value%16)), no  output  (Delta
                     Data)

     Consider the Hewlett-Packard 2645, which, to get to row 3 and column  12,
     needs  to  be sent "\E&a12c03Y" padded for 6 milliseconds.  Note that the
     order of the row and column coordinates is reversed here and that the row
     and  column  are  sent  as two-digit integers.  Thus its cm capability is
     "cm=6\E&%r%2c%2Y".

     The Microterm ACT-IV needs the current row and column sent simply encoded
     in binary preceded by a ^T, "cm=^T%.%.".  Terminals that use "%." need to
     be able to backspace the cursor (le) and to move the cursor up  one  line
     on  the  screen (up).  This is necessary because it is not always safe to
     transmit \n, ^D, and \r, as  the  system  may  change  or  discard  them.
     (Programs  using  termcap  must  set  terminal modes so that tabs are not
     expanded, so \t is safe to send.  This turns out to be essential for  the
     Ann Arbor 4080.)

     A final example is the Lear Siegler ADM-3a, which offsets row and  column
     by a blank character, thus "cm=\E=%+ %+ ".



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