_guide

= HScript language guide =

#order: -10

[List of HScript commands|/commands/]

== Variables ==

In HScript, you can assign strings to variables with the set command:

Set a variable: set x = "hello"

Set a global variable: set -g x = "hello"

or

`setenv x = "hello"`

Unset a variable: set -u x

A variable name must begin with letter or an underscore (_), followed by any number of letters, numbers or underscores.

To use a variable in a command, prefix its name with a dollar sign ($):

{{{

set foo = "bar" echo $foo bar }}}

You can optionally enclose the name of the variable in curly braces ({}) to prevent the variable name from running into surrounding text:

{{{

echo ${foo}baz barbaz }}}

In addition, when you use curly braces HScript will expand variable references in the name before looking up its value. This lets you simulate simplistic arrays:

{{{ set foo1 = Padma set foo2 = Mohammed for i = 1 to 2 echo ${foo$i} end Padma Mohammed }}}

In HScript, variables can be local or global (sometimes called system variables).

Local variables are local to the script being run. When the script is finished, the variable disappears. Local variables cannot be used outside the script in which they're defined. To create or set a local variable, use set. The variables created by the for and foreach loops are always local.

Global variables are available to all scripts and to any programs started by Houdini. To create or set a global variable, use setenv or set -g.

=== Variable modifiers === (modifiers)

You can add modifiers to the end of variable names to edit the returned value. These modifiers do not change the value stored in the variable, they only change the value returned by the variable reference with the modifier.

To modify the variable value, add :<<code>> to the end of the variable name. For example:

{{{

set afile = /home/matt/bin/foo.bar echo $afile:e bar echo ${afile:e} bar }}}

The available codes are:

:h: (Head) The path part of a pathname (that is, the path up to the filename).

{{{
> echo ${afile:h}
/home/matt/bin
}}}

:t: (Tail) Just the filname part of a pathname.

{{{
> echo ${afile:t}
foo.bar
}}}

:e: The extension on the end of the filename.

{{{
> echo ${afile:e}
bar
}}}

:r: (Root) All parts of a pathname except the extension.

{{{
> echo ${afile:r}
/home/matt/bin/foo
}}}

:s/<<ptrn>>/<<repl>>/: Substitute occurrences of pattern <> with <>. See the :g and :a modifiers below.

{{{
> echo ${afile:s}/foo/baz/
/home/matt/bin/baz.bar
}}}

:u: Convert the value to uppercase. See the :g and :a modifiers below.

{{{
> set str = Hello There
> echo ${str:u}
HELLO THERE
}}}

:l: Convert the value to lowercase. See the :g and :a modifiers below.

{{{
> set str = Hello There
> echo ${str:l}
hello there
}}}

Use the following prefixes to modify the behavior of the codes:

:g: (Global) Treat the string as a whitespace-delimited list of strings, and apply the following code to each component independently.

:a: (All) Recursively apply the following code as many times as possible.

For example:

{{{ #!hscript set A = "foo1 foo2 foo3 foofoo4"

$A:u == "Foo1 foo2 foo3 foofoo4" $A:u:u == "FOo1 foo2 foo3 foofoo4" $A:gu == "Foo1 Foo2 Foo3 Foofoo4" $A:gu:u == "FOo1 Foo2 Foo3 Foofoo4" $A:au == "FOO1 FOO2 FOO3 FOOFOO4"

$A:s/foo/bar/ == "bar1 foo2 foo3 foofoo4" $A:s/foo/bar/:s/foo/bar/ == "bar1 bar2 foo3 foofoo4" $A:gs/foo/bar/ == "bar1 bar2 bar3 barfoo4" $A:as/foo/bar/ == "bar1 bar2 bar3 barbar4" }}}

== Put the output of a command in a variable ==

Unlike expression functions, HScript commands are not functions and do not have return values. They just print output to the textport. If you try to assign the result of a command to a variable, as in: