Procedures defined by the proc statement can recursively call other procedures. They can be referred to inside an expression or as a new command, in which case any value returned is written to stdout. There is an implicit return statement at the end of every procedure definition.
The proc statement with no arguments prints a list of all the procedures that have been defined; if the argument is a name, that one procedure is listed; if the argument is a pattern, all procedures whose names match the pattern are listed.
unproc namelist, where namelist is a series of names separated by commas, discards the specified procedures. unproc pattern discards all procedures whose names match the pattern.
Builtin procedures
Expression operators
Wildcard characters
Tutorial: Procedures
Tutorial: Programming constructs
Tutorial: Expressions
Tutorial: Wildcarding