1tclsh(1) Tcl Applications tclsh(1)
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8 tclsh - Simple shell containing Tcl interpreter
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11 tclsh ?-encoding name? ?fileName arg arg ...?
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16 Tclsh is a shell-like application that reads Tcl commands from its
17 standard input or from a file and evaluates them. If invoked with no
18 arguments then it runs interactively, reading Tcl commands from stan‐
19 dard input and printing command results and error messages to standard
20 output. It runs until the exit command is invoked or until it reaches
21 end-of-file on its standard input. If there exists a file .tclshrc (or
22 tclshrc.tcl on the Windows platforms) in the home directory of the
23 user, interactive tclsh evaluates the file as a Tcl script just before
24 reading the first command from standard input.
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28 If tclsh is invoked with arguments then the first few arguments specify │
29 the name of a script file, and, optionally, the encoding of the text │
30 data stored in that script file. Any additional arguments are made
31 available to the script as variables (see below). Instead of reading
32 commands from standard input tclsh will read Tcl commands from the
33 named file; tclsh will exit when it reaches the end of the file. The
34 end of the file may be marked either by the physical end of the medium,
35 or by the character, “\032” (“\u001a”, control-Z). If this character
36 is present in the file, the tclsh application will read text up to but
37 not including the character. An application that requires this charac‐
38 ter in the file may safely encode it as “\032”, “\x1a”, or “\u001a”; or
39 may generate it by use of commands such as format or binary. There is
40 no automatic evaluation of .tclshrc when the name of a script file is
41 presented on the tclsh command line, but the script file can always
42 source it if desired.
43 If you create a Tcl script in a file whose first line is
45 #!/usr/local/bin/tclsh
46 then you can invoke the script file directly from your shell if you
47 mark the file as executable. This assumes that tclsh has been
48 installed in the default location in /usr/local/bin; if it is
49 installed somewhere else then you will have to modify the above line to
50 match. Many UNIX systems do not allow the #! line to exceed about 30
51 characters in length, so be sure that the tclsh executable can be
52 accessed with a short file name.
53 An even better approach is to start your script files with the follow‐
55 ing three lines:
56 #!/bin/sh
57 # the next line restarts using tclsh \
58 exec tclsh "$0" "$@"
59 This approach has three advantages over the approach in the previous
60 paragraph. First, the location of the tclsh binary does not have to be
61 hard-wired into the script: it can be anywhere in your shell search
62 path. Second, it gets around the 30-character file name limit in the
63 previous approach. Third, this approach will work even if tclsh is
64 itself a shell script (this is done on some systems in order to handle
65 multiple architectures or operating systems: the tclsh script selects
66 one of several binaries to run). The three lines cause both sh and
67 tclsh to process the script, but the exec is only executed by sh. sh
68 processes the script first; it treats the second line as a comment and
69 executes the third line. The exec statement cause the shell to stop
70 processing and instead to start up tclsh to reprocess the entire
71 script. When tclsh starts up, it treats all three lines as comments,
72 since the backslash at the end of the second line causes the third line
73 to be treated as part of the comment on the second line.
74 You should note that it is also common practice to install tclsh with
76 its version number as part of the name. This has the advantage of
77 allowing multiple versions of Tcl to exist on the same system at once,
78 but also the disadvantage of making it harder to write scripts that
79 start up uniformly across different versions of Tcl.
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83 Tclsh sets the following Tcl variables:
84 argc Contains a count of the number of arg arguments (0 if
86 none), not including the name of the script file.
87 argv Contains a Tcl list whose elements are the arg argu‐
89 ments, in order, or an empty string if there are no arg
90 arguments.
91 argv0 Contains fileName if it was specified. Otherwise, con‐
93 tains the name by which tclsh was invoked.
94 tcl_interactive
96 Contains 1 if tclsh is running interactively (no file‐
97 Name was specified and standard input is a terminal-like
98 device), 0 otherwise.
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102 When tclsh is invoked interactively it normally prompts for each com‐
103 mand with “% ”. You can change the prompt by setting the variables
104 tcl_prompt1 and tcl_prompt2. If variable tcl_prompt1 exists then it
105 must consist of a Tcl script to output a prompt; instead of outputting
106 a prompt tclsh will evaluate the script in tcl_prompt1. The variable
107 tcl_prompt2 is used in a similar way when a newline is typed but the
108 current command is not yet complete; if tcl_prompt2 is not set then no
109 prompt is output for incomplete commands.
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113 See Tcl_StandardChannels for more explanations.
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117 encoding(n), fconfigure(n), tclvars(n)
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121 argument, interpreter, prompt, script file, shell
122Tcl tclsh(1)