Not really a function. Returns the value of the last command in the sequence of commands indicated by BLOCK. When modified by a loop modifier, executes the BLOCK once before testing the loop condition. (On other statements the loop modifiers test the conditional first.)
A deprecated form of subroutine call.
Uses the value of EXPR as a filename and executes the contents of the file as a Perl script. Its primary use is to include subroutines from a Perl subroutine library.
is just like
except that it's more efficient, more concise, keeps track of the current filename for error messages, and searches all the -I libraries if the file isn't in the current directory . It's the same, however, in that it does reparse the file every time you call it, so you probably don't want to do this inside a loop.
Note that inclusion of library modules is better done with the use() and require() operators.