HOW TO CHANGE THE TITLE OF AN XTERM

Richard Lister, [email protected]



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


    _________________________________________________________________

  _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._
    _________________________________________________________________

    * 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


    _________________________________________________________________

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.


    _________________________________________________________________

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.


    _________________________________________________________________

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').


    _________________________________________________________________

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


    _________________________________________________________________

Credits

  Thanks to the following people.

  Paul D. Smith <[email protected]> and Christophe Martin
         <[email protected]>
         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 <[email protected]>
         suggested the use of \[...\] in the bash prompt for embedding
         non-printing characters.

  Christophe Martin <[email protected]>
         provided the solution for ksh.

  Keith Turner <[email protected]>
         supplied the escape sequences for Sun cmdtool and shelltool.


    _________________________________________________________________

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