Perl 5 version 24.0 documentation
- do BLOCK
Not really a function. Returns the value of the last command in the sequence of commands indicated by BLOCK. When modified by the
untilloop modifier, executes the BLOCK once before testing the loop condition. (On other statements the loop modifiers test the conditional first.)
- do EXPR
Uses the value of EXPR as a filename and executes the contents of the file as a Perl script.
- do 'stat.pl';
is largely like
- eval `cat stat.pl`;
except that it's more concise, runs no external processes, keeps track of the current filename for error messages, searches the @INC directories, and updates %INC if the file is found. See @INC in perlvar and %INC in perlvar for these variables. It also differs in that code evaluated with
do FILEcannot see lexicals in the enclosing scope;
eval STRINGdoes. 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.
If do can read the file but cannot compile it, it returns undef and sets an error message in $@ . If do cannot read the file, it returns undef and sets $! to the error. Always check $@ first, as compilation could fail in a way that also sets $! . If the file is successfully compiled, do returns the value of the last expression evaluated.
You might like to use do to read in a program configuration file. Manual error checking can be done this way: