Using -i inside a program

• Using the -i facilities from inside a program requires a little trick

• The files that -i operates on are the ones named in @ARGV

• The special $^I variable holds the backup file suffix

  • (Empty string if no backup)

• To engage -i, set up @ARGV and $^I and run a while <> loop:

        sub delete_user {
          my ($file, $target_user) = @_;
          local $^I = ".bak";
          local @ARGV = ($file);
          while (<>) {
            my ($user) = split /:/;
            print unless $user eq $target_user;
          }
        }

• Now the opening and renaming are all implicit

• Use local so that $^I and @ARGV recover their old values when the function is done

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Copyright © 2003 M. J. Dominus