Est. read time: 1 minute | Last updated: July 17, 2024 by John Gentile



Tcl can be easy installed with most package managers and may already be on a given system. The command line interpreter can be run in the shell as $ tclsh [script] to run a Tcl script or, when no arguments are passed, can run as an interactive shell to run Tcl commands.

Command Reference

Standard Output

puts is used to print text to standard output and comments are signified by # characters.

puts "Hello, World" # comment
# comments can also happen directly after semicolons
puts HelloWord; comment after semicolon

Assigning Values to Variables

Tcl is a quick and easy language for scripting since it is weakly typed; values and variable assignment types can be inferred without explicit conversions. In Tcl the set var val command puts the contents of val in the memory space of the first argument var. $ is used to tell Tcl to use the value of the variable.

set X "string value"

set Y 3.14 # numeric value
puts "The value of Y is $Y"

The \ backslash character is used to escape variable substitution for example:

puts "\$X" ;# outputs the string literal "$X" instead of the value in the variable `X`