alias

Synopsis:
alias [ [-]<alias name> [<commands>] ]

Description:
alias is one of TekNap's most powerful user interfaces. It allows the user to execute an arbitrary series of commands with one single command.
It actually serves a dual purpose. The primary usage is as described, a convenient mechanism for issuing multiple commands in succession. It may also be used to define custom functions that can be used in conditional or assignment statements. The real power of aliases comes from the fact that the client allows aliases to overload built-in commands (but not built-in functions).

Usage
Aliases are used just like normal commands (and functions). They may be called from the input line by prepending the command character (see cmdchars) to them, or may be used in a script. Likewise, scripted functions may be called using the normal $name( ) notation. Aliases have no functional differences between built-in commands and functions.

Syntax
Alias definitions with multiple commands may delimit the commands with semicolons, or the commands may span multiple lines if surrounded with curly braces. Users familiar with C/C++ or Perl programming will note numerous similarities in the command syntax. Like those languages, routines and functions are distinguished by whether the alias has a return value; functions do, routines don't. Aliases of both types may also accept arbitrary parameters, called expandos. They are used just like variables, and are numbered sequentially, starting with 0 (zero). Current aliases may be displayed by only giving the alias name in the command; all aliases matching the name are returned (such that "foo" might return aliases "foo" and "foobar"). If no alias name is given, all aliases are displayed. An alias may be removed by prepending its name with a hyphen (-). As mentioned previously, the client's builtin commands may be overloaded by aliases. This naturally poses a problem when one needs to use the real command, and needs to be sure it isn't some alias. The simple answer is to use the "//command" form. That is, the client will skip alias expansion for any command when it is preceded by the any command character twice. Other methods include stack, or avoiding command overloading in the first place.

Examples:
To create an alias that overloads a command, and calls it too:
alias lusers {
..echo ======= User Information for ${ [$*] ? [$*] : S}
..//lusers $* echo ======= End User Information
}

To create a function that returns the sum of two inputs:
alias sum {
..@ function_return = [$0] + [$1]
}

To create an alias that uses the new function:
alias showsum {
..echo *** The sum of $0 and $1 is $sum($0 $1)
}

An alternate way of definite the same alias:
alias showsum echo The sum of $0 and $1 is $sum($0 $1)

To use the new /showsum command to compute a sum:
/showsum 4 5
Using the alias as in the previous example will display the following:
*** The sum of 4 and 5 is 9

See Also:
assign
say
send
set cmdchars
stack

Restrictions:
As mentioned above, aliases can overload commands, but not functions. Alias names can consist of any character that isn't already a meta character for TekNap (the @ symbol, square brackets, curly braces, semi-colons, parenthesis, etc.). Note, however, that functions will not when the name contains certain characters. A good rule of thumb is to limit alias names to alphanumeric characters (and the underscore).

Bugs:
The exact syntax rules for alias structures (see assign for information about structures) is somewhat ambiguous. Structures can be represented as either name.sub or name[sub], but neither notation is guaranteed to work in all instances. Functions, for instance, do not work with the latter. This isn't necessarily a bug, but a feature of the syntax that may produce some unexpected results.

Other Notes:
Like C, whitespace in scripts is generally not significant (there are exceptions, such as with literal text to be echoed). An alias can literally be defined on one line, or on as many lines as desired. Code indentation is not required, though is done by convention, as with most structured languages. Braces in multiline aliases may be placed anywhere, as in C.

Back