tclsh - Simple shell containing Tcl interpreter


   tclsh ?-encoding name? ?fileName arg arg ...?


   Tclsh  is  a  shell-like  application  that reads Tcl commands from its
   standard input or from a file and evaluates them.  If invoked  with  no
   arguments  then  it  runs  interactively,  reading  Tcl  commands  from
   standard input and printing  command  results  and  error  messages  to
   standard output.  It runs until the exit command is invoked or until it
   reaches end-of-file on its standard input.   If  there  exists  a  file
   .tclshrc  (or  tclshrc.tcl  on  the  Windows  platforms)  in  the  home
   directory of the user, interactive tclsh evaluates the file  as  a  Tcl
   script just before reading the first command from standard input.


   If tclsh is invoked with arguments then the first few arguments specify
   the name of a script file, and, optionally, the encoding  of  the  text
   data  stored  in  that  script  file. Any additional arguments are made
   available to the script as variables (see below).  Instead  of  reading
   commands  from  standard  input  tclsh  will read Tcl commands from the
   named file;  tclsh will exit when it reaches the end of the file.   The
   end of the file may be marked either by the physical end of the medium,
   or by the character, "\032" ("\u001a", control-Z).  If  this  character
   is  present in the file, the tclsh application will read text up to but
   not  including  the  character.   An  application  that  requires  this
   character  in  the  file  may  safely  encode  it as "\032", "\x1a", or
   "\u001a"; or may generate it by use  of  commands  such  as  format  or
   binary.   There is no automatic evaluation of .tclshrc when the name of
   a script file is presented on the tclsh command line,  but  the  script
   file can always source it if desired.

   If you create a Tcl script in a file whose first line is


   then  you  can  invoke  the script file directly from your shell if you
   mark the  file  as  executable.   This  assumes  that  tclsh  has  been
   installed  in  the  default  location  in  /usr/local/bin;   if  it  is
   installed somewhere else then you will have to modify the above line to
   match.   Many  UNIX systems do not allow the #! line to exceed about 30
   characters in length, so be sure  that  the  tclsh  executable  can  be
   accessed with a short file name.

   An  even  better  approach  is  to  start  your  script  files with the
   following three lines:

          # the next line restarts using tclsh \
          exec tclsh "$0" ${1+"$@"}

   This approach has three advantages over the approach  in  the  previous
   paragraph.  First, the location of the tclsh binary does not have to be
   hard-wired into the script:  it can be anywhere in  your  shell  search
   path.   Second,  it gets around the 30-character file name limit in the
   previous approach.  Third, this approach will work  even  if  tclsh  is
   itself  a shell script (this is done on some systems in order to handle
   multiple architectures or operating systems:  the tclsh script  selects
   one  of  several  binaries  to run).  The three lines cause both sh and
   tclsh to process the script, but the exec is only executed by  sh.   sh
   processes the script first;  it treats the second line as a comment and
   executes the third line.  The exec statement cause the  shell  to  stop
   processing  and  instead  to  start  up  tclsh  to reprocess the entire
   script.  When tclsh starts up, it treats all three lines  as  comments,
   since the backslash at the end of the second line causes the third line
   to be treated as part of the comment on the second line.

   You should note that it is also common practice to install  tclsh  with
   its  version  number  as  part  of the name.  This has the advantage of
   allowing multiple versions of Tcl to exist on the same system at  once,
   but  also  the  disadvantage  of making it harder to write scripts that
   start up uniformly across different versions of Tcl.


   Tclsh sets the following global Tcl  variables  in  addition  to  those
   created  by the Tcl library itself (such as env, which maps environment
   variables such as PATH into Tcl):

   argc           Contains a count of the number of arg  arguments  (0  if
                  none), not including the name of the script file.

   argv           Contains   a   Tcl  list  whose  elements  are  the  arg
                  arguments, in order, or an empty string if there are  no
                  arg arguments.

   argv0          Contains  fileName  if  it  was  specified.   Otherwise,
                  contains the name by which tclsh was invoked.

                  Contains  1  if  tclsh  is  running  interactively   (no
                  fileName was specified and standard input is a terminal-
                  like device), 0 otherwise.


   When tclsh is  invoked  interactively  it  normally  prompts  for  each
   command  with  "%  ".   You can change the prompt by setting the global
   variables tcl_prompt1 and tcl_prompt2.  If variable tcl_prompt1  exists
   then  it  must  consist of a Tcl script to output a prompt;  instead of
   outputting a prompt tclsh will evaluate the script in tcl_prompt1.  The
   variable  tcl_prompt2  is used in a similar way when a newline is typed
   but the current command is not yet complete; if tcl_prompt2 is not  set
   then no prompt is output for incomplete commands.


   See Tcl_StandardChannels for more explanations.


   auto_path(3tcl), encoding(3tcl), env(3tcl), fconfigure(3tcl)


   application, argument, interpreter, prompt, script file, shell


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