Chip 1998 September/CHIP Eylül 1998.iso/Slackwar/docs/mini/Xterm-Title

Text File | 1997-01-30 | 10.7 KB | 362 lines

                      HOW TO CHANGE THE TITLE OF AN XTERM

Richard Lister, [e-mail]



   $Revision: 1.6 $, Last modified: Wed Jan 7 14:34:31 EST 1998


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   _This document explains how to use escape sequences to dynamically
   change window and icon titles of an xterm. Examples are given for
   several shells, and the appendix gives escape sequences for some other
   terminal types._
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     * Where to find this document
     * Static titles
     * Dynamic titles
     * Examples for different shells
          + zsh
          + bash
          + tcsh
          + csh
          + ksh
     * Appendix: escapes for other terminal types
          + SGI wsh, xwsh and winterm
          + CDE dtterm
          + Sun cmdtool and shelltool
          + Example
     * Credits


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Where to find this document



   This document is now part of the Linux HOWTO Index and can be found at
   http://sunsite.unc.edu/LDP/HOWTO/mini/Xterm-Title.html.

   The latest version can always be found at
   http://www.giccs.georgetown.edu/~ric/howto/Xterm-Title.html.


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Static titles



   A static title may be set for any of the terminals xterm, color-xterm
   or rxvt, by using the -T and -n switches:

  xterm -T "My XTerm's Title" -n "My XTerm's Icon Title"

Dynamic titles



   Many people find it useful to set the title of a terminal to reflect
   dynamic information, such as the name of the host the user is logged
   into, the current working directory, etc.

   This may be done by using XTerm escape sequences. The following
   sequences are useful in this respect:

  ESC]0;_string_BEL    Set icon name and window title to _string_
  ESC]1;_string_BEL    Set icon name to _string_
  ESC]2;_string_BEL    Set window title to _string_

   where ESC is the _escape_ character (\033), and BEL is the _bell_
   character (\007).

   _Note_: these sequences apply to most xterm derivatives, such as
   nxterm, color-xterm and rxvt. Other terminal types often use different
   escapes; see the appendix for examples. For the full list of xterm
   escape sequences see the file ctlseq2.txt, which comes with the xterm
   distribution, or xterm.seq, which comes with the rxvt distribution.

   These escapes really need to be applied every time the prompt changes.
   This way the string is updated with every command you issue and can
   keep track of information such as current working directory, username,
   hostname, etc. Some shells provide special functions for this purpose,
   some don't and we have to insert the title sequences directly into the
   prompt string.


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Examples for different shells



   In all the examples below we test the environment variable TERM to
   make sure we only apply the escapes to xterms. We test for
   TERM=xterm*; the wildcard is because some variants (such as rxvt) can
   set TERM=xterm-color.

  zsh



   zsh provides some functions and expansions, which we will use:

  precmd ()   a function which is executed just before each prompt
  chpwd ()    a function which is executed whenever the directory is changed
  \e          escape sequence for escape (ESC)
  \a          escape sequence for bell (BEL)
  %n          expands to $USERNAME
  %m          expands to hostname up to first '.'
  %~          expands to directory, replacing $HOME with '~'

   There are many more expansions available: see 'man zshmisc'.

   Thus, the following inserted in ~/.zshrc will set the xterm title to
   "_username_@_hostname_: _directory_" ...

  case $TERM in
      xterm*)
          precmd () {print -Pn "\e]0;%n@%m: %~\a"}
          ;;
  esac

   This could also be achieved by using chpwd() instead of precmd().

  bash



   bash supplies a variable PROMPT_COMMAND which contains a command to
   execute before the prompt. This example (inserted in ~/.bashrc) sets
   the title to "_username_@_hostname_: _directory_":

  PROMPT_COMMAND='echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD}\007"'

   where \033 is the character code for ESC, and \007 for BEL. Note that
   the quoting is important here: variables are expanded in "...", and
   not expanded in '...'. So PROMPT_COMMAND is set to an unexpanded
   value, but the variables inside "..." are expanded when PROMPT_COMMAND
   is used.

   However, PWD produces the full directory path. If we want to use the
   '~' shorthand we need to embed the escape string in the prompt, which
   allows us to take advantage of the following prompt expansions
   provided by the shell:

  \u          expands to $USERNAME
  \h          expands to hostname up to first '.'
  \w          expands to directory, replacing $HOME with '~'
  \[...\]     embeds a sequence of non-printing characters



   Thus, the following produces a prompt of "bash$ ", and an xterm title
   of "_username_@_hostname_: _directory_" ...

  case $TERM in
      xterm*)
          PS1="\[\033]0;\u@\h: \w\007\]bash\$ "
          ;;
      *)
          PS1="bash\$ "
          ;;
  esac

   Note the use of \[...\], which tells bash to ignore the non-printing
   control characters when calculating the width of the prompt. Otherwise
   line editing commands get confused while placing the cursor.

  tcsh



   tcsh has functions and expansions similar to those of zsh:

  precmd ()   a function which is executed just before each prompt
  cwdcmd ()   a function which is executed whenever the directory is changed
  %n          expands to username
  %m          expands to hostname
  %~          expands to directory, replacing $HOME with '~'



   Unfortunately, there is no equivalent to zsh's print command allowing
   us to use prompt escapes in the title string, so the best we can do is
   to use shell variables (in ~/.tcshrc):

  switch ($TERM)
      case "xterm*":
          alias precmd 'echo -n "\033]0;${HOST}:$cwd\007"'
          breaksw
  endsw

   but this gives the directory's full path instead of using '~'. Instead
   you can insert the string in the prompt:

  switch ($TERM)
      case "xterm*":
          set prompt="%{\033]0;%n@%m:%~\007%}tcsh%% "
          breaksw
      default:
          set prompt="tcsh%% "
          breaksw
  endsw

   which sets a prompt of "tcsh% ", and an xterm title and icon of
   "_username_@_hostname_: _directory_". Note that the "%{...%}" must be
   placed around escape sequences (and cannot be the last item in the
   prompt: see 'man tcsh' for the details).

  csh



   This is very difficult indeed in csh, and we end up doing something
   like the following (in ~/.cshrc):

  switch ($TERM)
      case "xterm*":
          set host=`hostname`
          set user=`whoami`
          alias cd 'cd \!*; set prompt="^[]0;${user}@${host}: ${cwd}^Gcsh% "'
          breaksw
      default:
          set prompt='csh% '
          breaksw
  endsw

   where we have had to alias the cd command to do all the work of
   setting the prompt. Note that the '^[' and '^G' in the prompt string
   are single characters for ESC and BEL (can be entered in emacs using
   'C-q ESC' and 'C-q C-g').

   I strongly recommend abandoning csh in favour of a more advanced
   shell: zsh, bash or tcsh.

  ksh



   ksh provides little in the way of functions and expansions, so we have
   to insert the escape string in the prompt to have it updated
   dynamically. This example produces a title of "_username_@_hostname_:
   _directory_" and a prompt of "ksh$ ".

  case $TERM in
      xterm*)
          HOST=`hostname`
          PS1='^[]0;${USER}@${HOST}: ${PWD}^Gksh$ '
          ;;
      *)
          PS1='ksh$ '
          ;;
  esac

   However, PWD produces the full directory path. We can remove the
   prefix of $HOME/ from the directory using the ${...##...} construct.
   We can also use ${...%%...} to truncate the hostname:

  HOST=`hostname`
  HOST=${HOST%%.*}
  PS1='^[]0;${USER}@${HOST}: ${PWD##${HOME}/}^Gksh$ '

   Note that the '^[' and '^G' in the prompt string are single characters
   for ESC and BEL (can be entered in emacs using 'C-q ESC' and 'C-q
   C-g').


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Appendix: escapes for other terminal types

  SGI wsh, xwsh and winterm



   These terminals set TERM=iris-ansi and use the following escapes:

  ESC P 1 .y _string_ ESC \\        Set window title to _string_
  ESC P 3 .y _string_ ESC \\        Set icon title to _string_

   For the full list of xwsh escapes see xwsh(1G).

  Sun cmdtool and shelltool



   cmdtool and shelltool both set TERM=sun-cmd and use the following
   escapes:

  ESC ] l _string_ ESC \            Set window title to _string_
  ESC ] L _string_ ESC \            Set icon title to _string_

   These are truly awful programs: use something else.

  CDE dtterm



   dtterm sets TERM=dtterm, and appears to recognise both the standard
   xterm escape sequences and the Sun cmdtool sequences. (I've only
   tested this on a Sun ... anyone have HP and DEC versions they can test
   for me?).

  Example



   Here's my full setup using zsh to handle all these terminal types:

  case $TERM in

    xterm*|dtterm)
      precmd () {print -Pn "\e]0;%n@%m: %~\a"}  ## window & icon title
      ;;

    iris-ansi)
      precmd () {
        print -Pn "\eP1.y%n@%m: %~\e\\"         ## window title
        print -Pn "\eP3.y%n@%m: %~\e\\"         ## icon title
      }
      ;;

    sun-cmd)
      precmd () {
        print -Pn "\e]l%n@%m: %~\e\\"           ## window title
        print -Pn "\e]L%n@%m: %~\e\\"           ## icon title
      }
      ;;

  esac


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Credits

   Thanks to the following people.

   Paul D. Smith <[e-mail]> and Christophe Martin
          <[e-mail]>
          both pointed out that I had the quotes the wrong way round in
          the bash PROMPT_COMMAND. Getting them right means variables
          _are_ expanded dynamically.

   Paul D. Smith <[e-mail]>
          suggested the use of \[...\] in the bash prompt for embedding
          non-printing characters.

   Christophe Martin <[e-mail]>
          provided the solution for ksh.

   Keith Turner <[e-mail]>
          supplied the escape sequences for Sun cmdtool and shelltool.


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