Is there a way to get the current file handle that would be used with the <> operator in perl?-CodePudding

I've seen that close ARGV can close the currently processed file, but it would seem that ARGV isn't actually a file handle, so I can't use it in a read call. Is there any way to get the current file handle, or am I going to have to explicitly open the files myself?

CodePudding user response：

... but it would seem that ARGV isn't actually a file handle, so I can't use it in a read call

ARGV is a filehandle and it can be used within read.

To cite from perlvar:

... a plain filehandle corresponding to the last file opened by <>"*

So it is a filehandle and it can be used within read. But you need to have to use <> first so that the file gets actually opened. And it will not magically continue with the next file as <> would do.

To test simply do (UNIX shell syntax, you might need to adapt this for Windows):

perl -e '<>; read(ARGV, my $buf, 10); print $buf' file

The <> will open the given file and read the first line. The read then will read the next 10 bytes from the same file.

CodePudding user response：

<> is short for readline( ARGV ).

The file handle used is ARGV.

However, readline has special code to open/reopen ARGV which read doesn't have.

You can, however, achieve a read using readline by manipulating $/.

$ echo abcdef | perl -Mv5.14 -e'local $/ = \2; $_ = <>; say "<<$_>>";'
<<ab>>

$ perl -Mv5.14 -e'local $/ = \2; $_ = <>; say "<<$_>>";' <( echo abcdef )
<<ab>>