Tcl Hello World Example: How To Write, Compile and Execute Tcl Program on Linux OS

Question: I would like to understand the basics of how to write and execute Tcl program on UNIX / Linux OS. Can you explain it with a simple example?

Answer: In this article, let us review very quickly how to write a basic Hello World Tcl program and execute tcl program on Linux or Unix OS.

1. Write a Hello World Tcl Program

Create the helloworld program using the Vim editor as shown below.

$ vim helloworld.tcl
#!/usr/bin/tclsh

# hello world sample program
puts "Hello, World !"

Note: Comment in Tcl starts with #.

2. Make sure Tcl interpreter is installed on your system

Make sure Tcl interpreter is installed on your system as shown below.

$ whereis tclsh
tclsh: /usr/bin/tclsh /usr/bin/tclsh8.4 /usr/share/man/man1/tclsh.1.gz

Installing tcl interpreter

If you don’t have tcl interpreter, install it as shown below.

$ sudo apt-get install tcl8.4

3. Execute Tcl Program

You can either execute using “tclsh helloworld.tcl” or “./helloworld.tcl”.

$ tclsh helloworld.tcl
Hello World!

( or )

$ chmod u+x helloworld.tcl

$ ./helloworld.tcl
Hello World!

Note: As Tcl is an interpreted language, you don’t have the compilation step similar to the C program.

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